A player's first kill in a new tank is always a hugely satisfying moment.
Navigating around the enemy's attacking and defending forces as a light tank and taking out the SPGs that have been hammering your allies is not only helpful to your team, but it is also very, very satisfying.
The most glorious variation of the above involves the light tank taking a hit that destroys the engine, but manages to keep speeding to safety because the tracks weren't hit. You know the Tank Gods love you when your engine-less light tank manages to slide into cover using the last bit of its own momentum.
Words can barely describe the awesome of a lone SPG crossing the field in Malinovka and capturing the enemy HQ while the enemy Tigers are only just approaching the friendly base from the flank.
The Kamikaze award is given for killing a higher-tier tank by ramming, normally a reckless maneuver to begin with, often resulting in the death of the person attempting it. Getting this award in an SPG, almost all of which are extremely fragile and don't do much ramming damage, is considered nigh impossible. Getting it in an SU-18 SPG, one of the slowest and most delicate vehicles in the game, is something very special.
Tank Destroyers are thin skinned beasts, usually, which makes it amazing when you get Steel Wall (take 11 or more hits with a total potential damage of at least one thousand damage). A Luck-Based Mission if there ever was one, but a damn amazing achievement, if you can manage it.
Especially since as soon as the fight begins, every single SPG is gonna open fire and turn the place into a wasteland followed by everyone else on both teams that can hit firing.
Top Gun, Steel Wall, Reaper, Spartan. Getting any of the achievements is basically this for the player. Top Gun requires you to get six kills, Steel Wall requires you to take the most amount of damage on your team and survive (at least 1,000 damage and 11 shots), Reaper requires you to kill three or more enemies with one shot each, and Spartan requires you to more or less earn a Steel Wall and survive with ten percent or less of your health.
A note concerning Steel Wall: At one point many moons ago, it required that the player merely survive 1,000 damage before dying (or surviving the match), and take the largest amount of potential damage. These days? Take 1,000 damage and at least 11 hits, while still taking the largest amount of potential damage. And live.
Getting a decent team that knows what it´s doing and supports attacking teammates, rather than sit around camping because that tier 4 TD behind the corner could scratch their paintjob. It´s rare, but my god is it glorious when it happens.
Being in a 3-man platoon in very good tanks, becoming top tanks and just run around owning everybody and single-handedly winning the game makes you feel like you are on top of the world. There is now a medal for killing 12 enemies in a platoon, appropriately named 'Crucial Contribution'.
SPG's, due a rather long aiming time, tend to focus on Tank Destroyers, Heavy Tanks and enemy SPG's. However, a sign of a great arty gunner, or a lucky one, is hitting a light tank that's charging across the field at over 60kph.
Scout Achievements are a different kind of badass. They require the player to, against all common sense drive an undergunned and underarmored (and generally over-engined) tank into the line of fire of things that will annihilate you very quickly, if not in one hit. Getting Patrol Duty is a Scout's version of getting a Kolobanov's medal - spotting nine tanks and living. Note that, however, Scout and Patrol Duty medals are not restricted to Light Tanks - any vehicle with eyes can possibly get them. It's not unheard of for Heavy Tanks to get Scout medals.
Depends heavily on the map. On Sand River it is a milk run, on Malinovka it requires a good tank, an experienced player, and a lot of luck; on town maps like Himmelsdorf, it is nigh impossible.
Getting Ranger on a Tank Destroyer is generally one of the greatest moments of any tanker's life. You have to take down 3 individual light tanks, either by sniping a speeding target with a shell just slightly faster than them or take it out in close combat, where you need to bring your forward-facing cannon to bear against a far more agile opponent. Doing the former is a sign of Improbable Aiming Skills doing the latter makes you an Ace Pilot.
Using a Tank Destroyer to assassinate the enemy artillery through a long range direct fire shell is both ironic and highly awesome.
The best sign of a good sniper, is often either taking down an tank's weakpoint from long range, where it's barely even visible, taking out a light tank as per above, or shooting a tank that's not spotted. In most cases, this is because the tank just realized it's been spotted, and is now hauling ass. Good snipers will hope for a tracking shot and aim for one, if that fails great snipers will then proceed to gauge where their target is, load another shell, and shoot the now invisible tank. Artillery have massive AOEs to work with, doing so with a sniper means perfectly leading an invisible target.
Getting any epic medal, which require feats of pure badassery or being Weak, but Skilled:
Finishing off the last tank with one hitpoint left on you is immensely satisfying, as well as completely awesome.
A better achievement: Fadin's Medal - being able to kill the last enemy with your very last shell
Attaining the Pascucci's Medal is a Once in a Blue Moon achievement: first, you must be in a battle where there are at least three artillery units on the enemy's side; and two, you must kill at least three of them. Getting that in a light tank is relatively easy; getting it in a heavy tank is another, but it will leave a very wide grin on the player if it happens. There's also awards for four and five artillery kills, five being the hard cap for artillery per team.
A light tanker can get a two-for-one and obtain the Tamada Yoshio's Medal if they're two tiers under the SP Gs. A heavy tank going for Pascucci's at least stands a chance of surviving any desperation shots and will kill a SPG in one or two hits. Light tanks will die instantly to a direct hit and usually take a few extra shots to finish a SPG.
A few epic medals are obtained by taking out opponents that are at least two tiers higher than you: Lehväslahio's/Oskin's/Nicols's for 2/3/4 kills in a Medium tank, Orlik's for three kills in a light tank, and Halonen's for three kills in a tank destroyer. All of these medals, as a base requirement, require the player to be one of the weakest tanks on the team and still contributing.
Anybody ever that gets Kolobanov's Medal; it's only awarded to those that "Stand alone against 5 or more enemy tanks and SPGs and wins." Note that that is not "beat 5 enemy tanks without assistance", this is you being the last person on your team against 5+ opponents and winning anyways. Previously, this required you to face off against nine or more opponents.
Getting 14 or 15 kills, in a random game where are only a total of 15 enemy tanks, will net the Raseiniai Heroes' medal, based on a Real Life incident where a KV-2 held back an entire Panzer division.
Billotte's, Bruno's, and Tarczay's: For players that still kick ass even in a crippled tank. Requires the tanker to take damage to at least 5 modules or crewmen, lose 80% of their HP, and still kill at least two tanks.
Arty finally gets in on the epic medal action with the 9.1 patch. Stark's requires that the SPG user not only score two kills but that they are hit twice and lose 2/3rds of their HP in a vehicle that is often killed in one shot. Gore's is simply a damage medal... requiring 10 times the SPG's health, in a tank that shoots every 25-60 seconds at best.