TheCrystalTheme. AKA the Prelude. It's even more awesome when you realize it was a Throw It In; the song took Uematsu all of ten minutes to put it together. It's normally either the first music you hear in a Final Fantasy game or the last.
The Dissidia version of the Prelude is incredibly beautiful, sounding like a mixture of all the versions made so far.
And now that XIV's take on the Prelude is out, it's not too much of a stretch to say Uematsu seems to keep building on one of the classic tunes in gaming music history in pleasing ways. It's also incredibly soothing.
Every main entry in the series (besides XIII-2 and XIV) have "Piano Collections" albums, which are (for the most part) solo piano versions of the more memorable pieces. They are fairly advanced arrangements (and the sheet music is available for most of them) and a good number of them sound amazing, if only for the sheer virtuosity required to play them.
The arrangement of Temple of Chaos heard here sends shivers up the neck. What's more amazing is that the orchestral concert it originates from was held in 1989. Videogame music is Serious Business in Japan.
There's also Last Battle, Boss Battle A, and the latter's remix in Boss Battle B. Although none of these existed until the remakes (the original merely used the standard battle theme on all enemies including bosses), they still deserve a mention here.
Let Me Know the Truth, known as Pavillion of Dorga and Une in the remake. The piece is already amazing enough in its 8-bit incarnation, but when Tsuyoshi Sekito and Keiji Kawamori arrange it with an orchestra at their disposal, it just ascends to another level of awesomeness. The hidden version from FFIX is brilliant too.
The remake's team took the already amazing 'Crystal Tower' theme and made it better.  Sekito's also responsible for II's redone soundtrack, and it's AWESOME.
S.S.H. and The Dual Dragons have both made their own metal versions of this theme, each with its own extra dash of intensity and awesomeness.
The Final Fantasy IVMain Theme. Though it appears in several guises throughout the game, its main version, which plays in the overworld, captures just the right blend of adventurous and solemn to fit the game's overall tone.
TheDreadfulFight, and its Dissidia remix. Starts out imposing and awe-inspiring, then becomes frantic and adrenaline-charged, then wraps around to become imposing and awe-inspiring again. All told, the perfect music to accompany some of the game's most intense battles.
Red Wings, the intro theme. It speaks to this song's versatility that it evokes one emotion during Cecil's moral quandary at the beginning of the game and an entirely different emotion during the Red Wings' Big Damn Heroes moment.
The Tower of Bab-il, a dungeon so expansive in scope it requires its own theme to match. The rising and falling triplets in the strings under the trumpet melody help to strike just the right balance of urgency and grandeur.
A Long Way To Go; perhaps the perfect evocation of that sentiment in music. Also one of the pieces to seriously benefit from a remake, with the added snare drums kicking the message out.
And then there's the S.S.H. remix, which manages to actually surpass the original, while still maintaining its calm and beautiful feel - a feat which is made even more impressive when you consider what S.S.H. workstend to sound like.
There's also a heavy metal version in the Black Mages' third album. It even got put to a live actionplay in one of the Black Mages' concerts. To put it another way; the Black Mages did the Opera for real. Including the uninterrupted ending and the epic sword duel between Draco and Ralse.
Dancing Mad from Final Fantasy VI is especially notable because it samples at least three songs from earlier in the game, melding them together with some Bach to create the opera of madness. The fact that Nobuo Uematsu lists it as one of his favorites should be a tell-tale sign.
The final section of the song is particularly awesome. You've got a variation of Kefka's main theme, an Uncommon Time signature and a tempo change, not to mention Kefka's distinctive laugh as part of the music.
This detailed, critical analysis of Dancing Mad should be enough to make even the few who are left unimpressed by the music itself change their opinion and admit that it is an ingenious masterpiece conceived by an ingenious composer.
Tony Dickinson's contribution to OC Remix, "Prancing Dad", fuses together a combination of orchestral bombast, prog-rock-inspired guitar solos, and sections of "One-Winged Angel" to create an even more melodically complex epic of darkness and insanity.
"Epitaph," the flashback song just before getting the Falcon, and "Searching for Friends," the new world map theme just after. It comes just after the game has spent the last several hours hammering in the sheer hopelessness and gloom of your situation, and even gives you one more Tear Jerker in the form of just how Setzer got this spare airship from a lost love in the first place, complete with appropriately sad flashback music. But then... then Epitaph fades out, and Searching for Friends fades in just as Setzer declares that the Falcon just may save them all. On top of being a damn good song in general, it has this unmistakable aura of light-at-the-end-of-the-tunnel-style hope. Hearing this theme gives the message that all the sudden, you're back in the game, that you have one more chance. Even inside the game, Edgar declares "For once I feel hopeful!" Very powerful scene, the music absolutely makes it. See for yourself.
The ending theme — yes, all 20 minutes of it. Especially when the FF Main Theme kicks in towards the end.
That moment when Celes's Theme is playing, and Locke's Theme starts playing underneath it, in perfect sync. Chills.
And again when the simple whistle in Shadow's Theme is replaced by sweeping strings—as he decides to stay behind.
Speaking of tear jerkers, here is Gau's Theme, which only makes a few short appearances in the game. This is really too bad because Gau gets a nice orchestrated piece on the Final Fantasy VI: Grand Finale album.
A strange tune, but Gogo's awesome and so is his Theme.
Okay, so Celes's part in the opera is unmatchable, but the fitting yet suitably goofy Grand Finale, playing as the rest of your party and Ultros accidentally hijack the opera's ending by knocking out the actual leads and fighting for keeps over Celes—that's got to be worth something.
Not as well known, but Mt. Kolts remains an endearing song and makes you think you are going on some great adventure. Phantom Forest is also a very mellow but creepy song that will get embedded into you head.
There's also Dark World, which plays on the overworld in the World of Ruin before you get the Falcon, as well as in WoR Narshe. It's a musical piece that explains in so many ways that you failed to save the world, and this is your life right now.
While its "official" vocal version Pure Heart is only above average at best, katethegreat's and Choucho's renditions are indeed awesome. Bonus points to Choucho for using the orchestra version as her version's background music.
The timing of the music at certain points creates a CMOA. In Cloud's original flashback section, Sephiroth begins his murderous rampage through Nibelheim by dramatically announcing, "I'm going to see my mother." Cue spine-chilling theme song of pure evil. The scene's music is perfect because up until Sephiroth says that, the music in the mansion had been just the backing percussion and bell sounds... the rest of the theme kicks in as he leaves to go burn the place.
The true account of what happened in Nibelheim has dull, repetitive background music all the way through it until the point where Sephiroth stabs Cloud through the chest. The very moment that Cloud grabs Sephiroth's sword and begins to overpower him the music reaches a dramatic and beautiful swell and becomes appropriately heroic.
Nibelheim's theme: Anxious Heart. There's a reason it's called Anxious Heart. It's creepy, almost to the point of being downright nightmarish. It puts you on edge, and you can just tell something bad's gonna go down.
The Crisis Core remix, The Shrouded Village, is also excellent. Faster-paced and thus less overtly sinister than the original version, it gives a feel of the calm before the storm — and considering what's about to happen...
So not only is Mako Reactor a brilliantly atmospheric piece that plays in EVERY Mako reactor you go into, its Voices of the Lifestream remix, entitled No Such Thing As The Promised Land, manages to ramp the feeling and the badass up to 11. It becomes even better when you realize that the final section of Mako Reactor is a slight change from Aerith's Theme, played in a minor key to contrast the down-to-earth Aerith with the environmentally destructive reactors.
For those that enjoy hip-hop, rapper Random/Mega Ran lyrically narrates the game from (mostly) Cloud's point of view in his "Black Materia" album. It helps that the on-point lyrics are accompanied by some bangin' remixes of the game's soundtrack. Example: Mako Reactor.
Those Chosen by the Planet, Sephiroth's actual Leitmotif in the original game. Too bad it's been overshadowed by "One-Winged Angel" to the point that it's easy to forget that it incorporates the melody of "Those Chosen by the Planet".
Eyes On Me, the game's vocal theme, is a true Awesome Music. Not really for the game ending (which is a Heartwarming Moment by its own) but for the "Rinoa and Squall in space" scene. Seriously, that scene had a giant Narm potential. After all, by that point the game almost became an epic space opera, but when Rinoa is listening to the countdown of her oxygen, wondering if she will die, Squall saves her, they head home, and the song start playing, in a true Heartwarming Moment. The song saved the scene. Thus, it is awesome.
The Extreme. Used as the final boss music, it starts out with the opening verse of the aforementioned Liberi Fatali, then begins a very ominous piano piece, and finally shifts to the fast-paced theme proper, which sounds nothing short of amazing.
What makes the final battle especially awesome is the classic Final Fantasy riff that plays at the 1:39 mark in "The Extreme". It really kicks the song into high gear and lets you know that, yes, this is a Final Fantasy final battle - now go and slay that sorceress.
The fast-paced section that begins at 3:05 really conveys a sense of desperation and chaos - the heroes are being pushed beyond their limit by forces they can barely comprehend, but they still keep fighting.
With Ride On, the Ragnarok Theme, let's just say Selphie's not the only one exhilarated.
Premonition, most notably played during battles with Edea.
Fisherman's Horizon, the peaceful theme of the peace-loving town that share's the theme's name.
The orchestral version from Fithos Lusec Wecos Vinosec is unbelievably beautiful. In fact, that whole album is a CMoA for FFVIII remixes. Equally beautiful is the slightly-altered Distant Worldsremake.
Movin' is like the Final Fantasy version of "Powerhouse", that one piece of music used in Warner Bros cartoons anytime something resembling an assembly line occurs. Partially because its opening is set to a FMV, it goes on for a while before looping, which is unusual for FF songs built around a catchy chorus.
The Salt Flats, which is heard at the Great Salt Lake and the sorceress sealing facility (but only if you visit it before the plot demands).
The Spy, played in the Missile Base. It really feels like you're infiltrating some hideout and have to maintain cover.
There's an alternate version, entitled "Original Sin". It may seem fanmade at first, but perish the thought as this is official...but also removed content. It's quite possible that this was intended for the final battle instead of the version used in-game, but for some reason the above was instead used. "Original Sin" combines the melody of "Decisive Battle" with sections of "To Zanarkand" and the "Hymn of the Fayth", and to great effect.
Otherworld, which plays during the game's opening FMV and again when fighting Aeon Jecht. Even more awesome is the fact that the only reason Uematsu wrote it is because he's a fan of heavy metal and wanted to try writing a metal song himself. The lyric is also awesome, it pretty much sums up most of Tidus' journey in a nutshell.
The even more epic Braska's final aeon version. Sadly removed from the HD remasters. Has an awesome percussion addition not in the original and a different bassline.
Summoned Beast Battle, which plays when you fight your Aeons in the final battle. To hear the once tranquil and somber Hymn of the Fayth in such an effectively stirring rendition gives you chills and helps ease the pain of being forced to destroy your own Aeons.
Summoned Beast Battle also plays when you fight the Bonus Boss Penance. The tension of the music fits perfectly the fight.
Auron's Theme. Because he's such a bad-ass, he gets synthesiser music. It's also a bit of a Tear Jerker when it plays when he dissolves into pyreflies at the end of the game.
And a fan remix of this only ups the Tear Jerker factor, since it turns it into a sad, meditative guitar piece with dramatic strings and bass, plus a brassy ending quoting "At Zanarkand" that rivals the version which plays when Tidus and Yuna share their last ghostly embrace: Guardian's Sending.
For fan remixes, the conceptual piece The Final Summoning, building off the Hymn Of The Fayth and sheer fucking epic.
San d'Oria's town theme is not really a fan favorite (after a while, you get a little tired of hearing the backpipes). However, the past version of the town has its own fantastic and powerful theme, more lighthearted and definitly more well-liked: Griffons Never Die.
Giza Plains, a perfect companion to any start of a journey. It's almost as if the composers knew you were going to start a fight at the exact moment the song goes from adventurous and free-spirited to badass and rowdy.
The Battle For Freedom is the most epic, being the final boss song. Starting of as a tranquil strings, it later builds up the tension with percussion, and more strings. The buildup was so intense that when it comes to the centerpiece, you just had to prolong the battle to listen to the entirety all over again.
Esper, an epic remix of the aforementioned Esper Battle.
Eruyt Village is a just background music for a few towns. But it's so hauntingly beautiful and calming that it needs to be included here. It's the perfect theme to go with some of FFXII's most visually stunning locations.
Being the first location that Vaan can go to outside Rabanastre, the Dalmasca Estersands' theme conveys a real sweeping sense of freedom. Appropriate, given the comparatively open feel of FFXII's gameplay as compared to previous games in the series.
"Kiss Me Good-Bye" is the gorgeous and emotional theme song of the game. Luckily for us, it comes in twolanguages.
Fighting Fate, this Boss Battle theme in particular. Fits very nicely when fighting Galenth Dysley/Barthandelus.
The non-battle version of this theme, Ragnarok, which plays when the party is turned into l'Cie by Anima, is also good, as well as very haunting.
Born Anew is incredible as well. Nothing matches the adrenaline rush you get from 0:15-0:33 especially, which plays as Orphan rises out of its pool to battle you. The buildup on Nascent Requiem was quite exhilarating, and somehow the playful theme seems to be mocking the players.
The Sunleth Waterscape. Take the game's leitmotif tune, speed it up to a bubblegum pop rhythm, and throw in upbeat lyrics. This is what you'll get.
Atonement is a beautiful track that plays when Hope reconciles with Snow, and later on, when Snow reaffirms his commitment to save Cocoon. Other great tracks include This is Your Home, which plays when Bartholomew tells Hope that l'Cie be damned, Hope is his son...and that their home will always be a sanctuary for him, no matter what.
Eidolons and Test of the l'Cie, which play during the battles with the Eidolons, depending one which one you're facing, make this list easily.
Will to Fight was a perfect piece to play in Palumpolum after Hope realizes just how feared he is as an l'Cie. It truly evokes the emotions of how painful it must be for him to be looked on as a monster by his neighbours.
The Battle Results theme which plays after the game's victory fanfare is too awesome to be left out! (Normally, you guys'll just skip the results after each battle, shame that you missed such an alluring music...)
This list ain't complete without Desperate Struggle. Only plays during a handful of boss battles, but they're also some of the most intense battles in the game. Thus it doesn't matter when Cid Raines kicks your ass for the 100th time, because it just means you get to listen to this badass music even more.
The Archylte Steppe welcome players with a another use of the game's leimotif. Not only is it quite peaceful, but it conveys quite well the feeling that you are exploring a new, open-ended area, on top of being a new WORLD, filled with its own active fauna.
Neighboring area, the Yaschas Massif, rather clashes with the more serious feel of the steppe's theme, instead sounding rather cheerful and oddly elevatory. As with the steppe and its theme, this one makes exploring its own large area pleasant, to say nothing of the Scenery Porn.
Lake Bresha just oozes 'beginning of an adventure'. It's also damn catchy.
The Piano Collections version of the Sulya Springs theme, and the rest of the piano collections for this game as well. The way they transform the original songs into something very different, while still keeping the core melodies, and still sounding just as good, if not better.
The regular battle theme, The Saviour. Dat violin. And electric guitar is always good.
The final bossthemes against Bhunivelze, which is one of the greatest battles in the FF series overall and accompanies one of the most epic endings to a video game, as Lightning has to fight against the ruler of the FFXIII universe in a battle for the souls of all humanity. That choir will have you mesmerized.
Crimson Blitz is almost better than the original version of Blinded by Light.
As is to be expected from a place that chooses to call itself the "city of pleasure", every single one of the Yusnaan themes are an absolute blast to listen to. Special mention going to The Glittering City of Yusnaan and City of Revelry
Most of the records that play in Yusnaan are gorgeous: Ambivalence plays in the prologue, when Lightning has to chase Snow through his palace; Yusnaan Palace, when she infiltrates the palace for the second and final time; and High Voltage, which is one of the primary battle themes in the city.
A lot of the Luxerion themes count as well: The "straight-out of a noir film" Eternal Midnight, and Nova Chrysalia, which is a gorgeous, predominantly string piece that plays in the early morning hours.
Most of the Legacy city themes were "nice". Navigator's Glory, the theme of Limsa Lominsa, was awesome. Its only crime is being a little too short and thus tending to get a little tiresome if you spend a real long time in the city. But when you first got off the boat? Whoa.
Navigator's Glory was so awesome it was the theme song for the pre-release website for a long time.
The primal fights' songs all are incredible, and deserve a special mention:
When it was announced that Uematsu would not be contributing more tracks to XIV going forward after the leadership shake-up at the start of A Realm Reborn's development, people were worried. Who was going to replace him? Some guy named Masayoshi Soken? Who's he? He's never done a Final Fantasy game before! How could his music possibly be as good as the Maestro's? And then the Garuda fight was released. And we heard Fallen Angel. Everybody stopped worrying.
The full version of "Pharos Sirius" is wonderful. Particularly notable for being extended from a 1:30 song which only played when you entered the dungeon to a 5:23 song which now loops for the entire duration of said dungeon (adding two new movements to the original and repeating a couple portions). That is how awesome that song is, and the change was really appreciated.
For one of the most acclaimed dungeons of the game, mainly for its atmosphere and its resolution, you have the deliciously dark and haunting theme of Tam-Tara Deepcroft (Hard) which will send chills down your spine. Please note the subtle Buddhist chanting (and, once again, the One-Woman Wail).
Gilgamesh is back in FFXIV. Guess what remixed song plays when you fight him in-game (on an actual bridge, no less?). Ladies and gentlemen: Battle on the Big Bridge (FFXIV). Also, Enkidu is a rooster here. For reasons.
"Antidote" plays during the battle when you have Olan as a Guest Star Party Member. It also has no business being a battle theme, being nothing more or less than one of the most stirring waltzes ever written.
Other than Hitoshi Sakimoto's FFTA battle music, Kaori Ohkoshi composes one of the most epic songs in the game, including "Beyond the Wasteland" and "Surpassing the Wall". "Unavoidable Destiny", however, is the most epic.
There's also Determination which is a somewhat uplifting battle theme used for the Duelhorn storyline.
Looming Crisis. It helps that it plays during the incredibly epic battles against the Mage Kings of Ciquleur. The part starting at 0:40 is GODLY.
"Gathering Allies" is, and always will be, one of the catchiest tunes you hear as you fiddle around with your clan's equipment, jobs, and abilities. Dun-dun-duh-dadada-da-dun-dadada-da-dun-dah-dun-duuun...
And then there's the Limestone Quarry. That song hits you like a stone wall and never lets go.
"Fortress", which would have been a sequel to Final Fantasy XII taking place 10 years later, was a game that was cancelled by GRIN studios around 2009-2010. In February 2012, a track for it was released by composer Erik Thunberg, a truly majestic piece of music that evokes images of imperial splendor, palace intrigue, and a grand world. The artwork in the aforementioned Youtube link is of an older Princess Ashe. What Could Have Been, indeed.
Raem's original boss theme, "Sad Monster". It takes all the instruments used in all the previous songs in the game, and turns it into a song that really gets the blood pumping, readying you for the penultimate battle. Bonus points for the title actually being a Meaningful Name — Raem may seem like a Big Bad when you first hear him, but once you hand him his phoenix behind on a silver platter he becomes a whimpering, simpering creature whose only desire is to live . . . of course, he then eats his only companion and goes One-Winged Angel on you (leading to the epic Final Boss fight and the aforementioned "Unite, Descent"). Never have bagpipes been more epic.
The four elemental dungeon music tracks all provide the perfect atmosphere for their respective dungeons. The most recognisable is probably the hard rocking Lava Dome, complete with electric guitars, but the other three - the martial Bone Dungeon with its insistent snare drums, the enigmatic Ice Pyramid with its "wintry blast" sound effects, and the ominous Pazuzu's Tower with its tense string accompaniment - are also highlights.
Dissidia: Final Fantasy plays like a Greatest Hits album with some original work in there too... oh, right, there's also a game in there, but the music - original versions and kickass remixes - is mostly listed above for obvious reasons.
The ending theme takes the cake, though, remixing the ending themes of all the first ten games as scenes from each character's story play over the credits. It's enough to make a die hard fan tear up.
The Duodecimversion is the same concept, except that it takes Terra's theme as the piece representing FFVI (instead of Cyan's theme), adds pieces for FFXI, XII, and XIII and the Carmen Lucis track from the game itself, and is overall rearranged to pure awesome.
Still from Duodecim : Carmen Lucis. The first half is an awesome music of a desperate battle that ends up with seven Heroic Sacrifices, including one from Cosmos. The second half is plays when Shinryu revives the fallen warriors, with the Warrior of Light (not being dead) watching it, ending with Lightning's When She Smiles moment.
Even if the music of the Chocobo series are remixes from various tracks in the series, these are very epic remixes. For example Chocobo Racing has Mysidia's Sky Garden is the upbeat, fast-paced version of the dragon-riding track from Final Fantasy V.
Final Fantasy Fables: Chocobo Tales has some awesome tunes, most of which are remixes from other music, but mostly better then the originals. An example: The intro.
The Black Mages, Uematsu's rock band. They've produced some utterly amazing remixes of pretty much every track mentioned above, and then some.
Distant Worlds: Music From Final Fantasy, taking various tracks from all across the FF series and orchestrating them to awesome proportions. The whole soundtrack qualifies, but the ones of note are One-Winged Angel, Swing De Chocobo, Medley, and last but most definitely not least, Memoro DeLa Stono.
Many of the arrangements found on Distant Worlds first appeared on 20020220 Music from Final Fantasy, the live recording of a concert held in Tokyo in 2002. These arrangements would go on to be performed during the Dear Friends - Music from Final Fantasy concert tour in 2004 and 2005 and then used again during the Distant Worlds: Music from Final Fantasy concert series from 2007 to 2010. Which then brings them to the CD for Distant Worlds: Music from Final Fantasy.
Distant Worlds II and its subsequent world tour have brought an even greater selection of music to the orchestra hall, including the above-linked "Dancing Mad."
Heavy Metal Arrange Album GUARVAIL, taking tracks from a ton of the games and turning them into metal of awesomeness. The whole album is pretty sweet, but the ones of the most note are the arrangements of The Extreme, The FF Main Theme, Battle Scene A, and last but most definitely not least, DancingMad.
Nearly all of Love Will Grow, the Spiritual Successor to the aforementioned Final Fantasy: Pray album, belongs here.
The remixes from Sega Fantasy 6, a parody video taking the 7th Gen console wars and fitting them in flawlessly into Final Fantasy VI's last battle, deserve mentioning here.
CROW'S CLAW, known for its Touhou arranges, has also done some awesome remixes of Final Fantasy songs.
Final Fantasy Song Book: Mahoroba is the the sort-of-but-not-quite spiritual successor to Pray and Love Will Grow, being stylistically a bit different. And fantastic. (Examples including Evanecense (Home Sweet Home) and Maybe, Goodbye having the most unlikely theme, VII's "Farm Boy."