All of the Eeveelutions are good in their own ways, but here are the ones with the most of each stat:
Special Attack: Espeon/Glaceon (tie)
Special Defense: Umbreon/Sylveon (tie)
Umbreon, Sylveon and Vaporeon are the best defensive ones, Espeon and Jolteon are the best specially offensive ones, and Leafeon is the best physically offensive one. Flareon may have the best attack, but it doesn't get many good moves.
Source: DB Pokedex pages