Out of Vaporeon, Jolteon, Flareon, Espeon, Umbreon, Glaceon, and Leafeon, which eeveelution is simply the best in terms of stats, moves learned (including moves that can be learned by TMs/HMs), and of course appearance (which one looks the best).
Jolteon is the fastest and can run a variety of Special Attacking sets w/ the right hidden power.
Vaporeon and to an extent, Umbreon are really good defensive/support pokemon as they can learn moves such as wish, toxic, taunt, protect, and roar. Umbreon can also learn mean look which is cool if thats how you want to battle.
Leafeon is pretty underrated but awesome especially its swords dance set. However, it can also be a great physical wall.
Nate's Pokemon HeartGold FC: 0218 5058 8521 SBC Sky Gym Leader - Holder Of The Dojo, Selene, Alloy Badges