"A battle-ravaged Superman standing red-eyed with Cap's shield, chipped and cracked, along with Thor's hammer, which is radiating power giving the reader the 'So, who wants to slam dance with the first born son of God?' look as he stands on some patented Perez rubble. It sticks out from the rest of the series and makes the buyer want to read the comic." — Michael Bailey, JLA/Avengers #4 review
Seconded, especially because it makes perhaps the best image possible: DC's oldest and most iconic hero is leading the final charge, yes, but he needs the most recognizable objects in Marvel to do it. A good way of pleasing both fan-bases while being incredibly awesome.
Thor vs Superman, both rounds. The first round, Thor literally HAMMERS J'onn and Superman but the battle is inconclusive. The second round, Superman has Thor's measure, but Thor doesn't have his, so after a grueling battle, Superman manages to smack Thor down. As Aquaman gloats afterwards, Thor says that the next round with 'the Kryptonian' could go differently, implying that they're equally matched. A neat way to get around the usual fanboy rants on the subject.
And Superman says that "He... May be... Single toughest opponent... I've ever—" The missing word is fought, since the Avengers dogpiled him following that and unleashed a No-Holds-Barred Beatdown. Considering who Superman has fought down the years (Doomsday, Darkseid, Zod, Imperiex etc.) that's quite the accolade.
Aquaman then drives all of the Avengers away with a sea serpent. He's not letting them hurt Superman anymore than they'll let Superman hurt Thor.
Aquaman also manages to stun and incapacitate the attacking Atlanteans in the final battle. He makes a hilarious statement that they have minds a bit more complex than the average halibut. Luckily, Namor is half-Atlantean, so he just has a headache (a splitting one, though). Marrina isn't so lucky, though.
Flash and Hawkeye, both noted as being the comedy relief of their respective teams, saving the day. Even more awesome comes after this. Because of his actions, Hawkeye has been inducted as a member of the Justice League. Yes, Hawkeye is the only Marvel character to be a member of DC's premier superhero team, and the only character to ever be part of both.
"Oh, that arrow? Last one I had... a T.N.T. arrow."
Hal Jordan returns as The Spectre once Krona is defeated, forcing the twin Earths apart with his bare hands. Even Captain America is... impressed.
Hal Jordan's speech at the end of #3. Out of everyone there, he has the furthest to fall. And out of everyone there, he argues the hardest to Save Both Worlds. Good thing that man got a miniseries.
To top it off, he mentions they are not gods to meddle with reality as they see fit - which is exactly what he, as Parallax, tried to do in Zero Hour: Crisis in Time!. And Hal saw that he did that. That puts his argument in perspective, as it means he realized how wrong that is.
The single panel of Lobo easily manhandling the Shi'ar Imperial Guard.
The scene where the JLA tours Marvel-Earth, and Batman spends the entire scene telling everybody via J'onn's telepathy not to interfere, that they should just observe and move on — until Batman stumbles over the Punisher attempting to shoot some drug dealers. Batman's immediate response? Spend twenty minutes beating the stuffing out of the Punisher off-camera, and get chewed out by Plastic Man after-the-fact.◊ Also counts as a Funny Moment.
The moment when Captain America and Batman stopped fighting and decide to team up to find out just what exactly is going on. Or in other words, the foremost Badass Normal tactical super-geniuses of the Marvel and DC Universesnote Or slightly-above-normal in Captain America's case... teaming up to fight the bad guys. Really, at that point, the bad guys had already lost; all that remained was how close a thing it would be. Batman states Captain America might be able to beat him after a prolonged fight, he never outright confirms he would (though given the tone and Batman's general personality, it's usually taken as a very grudging admission).
Doubling as a Funny Moment, Vision comments that Red Tornado is just an android, so he'll stop him at its source by reaching inside and disrupting his machinery. Red Tornado comments, "Will you?"
Vision: Hm? Inside him? Circuitry— And something mooooorrrrrrrrreeee! (Vision gets flung away like a rag doll)
This makes Thor perk up and view Red Tornado as a Worthy Opponent. He never gets a chance to test Tornado's mettle, though, because Firestorm traps him while he snatches the MacGuffins of the round (the items of the Demons Three).
A villainous example. Krona almost beats Galactus to death in 3 hits.
Just about the entirety of book 4 is a CMOA really. The biggest clash of super villains and heroes in scope with a different treat at every panel. It was mind blowing.
On a related note, Captain America using Martian Manhunter's telepathic mindlink to organize and lead the ENTIRE combined force of heroes (essentially everyone who's ever been an Avenger OR a Justice Leaguer at one point), turning them into a well-honed superpowered army against the Villain forces. And until J'onn was removed by a reality shift, making it look easy. Thus demonstrating why Captain America is still one of the greatest Team Leaders of all time.
'One' of? This book confirms that Cap is the greatest leader both universes had to offer.
When deciding they would need co-ordination with their attack on Krona, Superman immediately nominates Captain America. Keep in mind, this was just after both had been raging at each other. It's a CMOA for both: Superman recognizing Cap's leadership, and Cap recognzing Superman's faith. (Superman really has no ego. Plus, maybe the defender of "Truth, Justice and the American way" was influenced by Cap's outfit.)
Captain America vs Prometheus, a villain who once took on and incapacitated almost the entire Justice League. The match lasts a whole of four panels.note Linkara was especially pleased it was the villain of Justice League: Cry for Justice getting a smackdown.
Cap: Neural chaff. Hypnotic lights. Pre-programmed skills. Try fighting the Wehrmacht, mister— It teaches you focus!
It's a mirror scene to Batman dealing with Batroc, who has supreme martial arts skills.note Considering Batman has dealt with Lady Shiva and Bronze Tiger, he's up to the task as well.
Though he lost, it's worth noting that even Batman admitted Batroc gave him a good fight, which counts as a minor one for ze Leapair. On top of managing to get a sucker punch (or kick) on the famously vigilant Dark Knight.
After Vision gives up the last of his strength to help Superman fight Radioactive Man and Solarr, Superman's a bit upset over this.
Hulk: Go ahead, puny-costume men! Blast Hulk again!
Wonder Woman collapses a section of Krona's base on top of some advancing Frost Giants, allowing the passing heroes to keep marching to Krona's control center, and pulls a You Shall Not Pass! on freaking Surtur. Mere moments later, her mother and She-Hulk drop by and join her.
Meanwhile, Batman dealing with a host of enemies, when Black Panther, Huntress and Black Widow offer their help. Bats just mildly comments that if they have nothing better to do, why not?
The Justice League and Avengers united, charging into battle, roaring in unison: "AVENGERS ASSEMBLE!" The panel is just awesome◊.
