I'm not mad about eeveelutions, but jolteon is my favourite of them. I remember that animé episode where arbok tried to use Wrap on a jolteon and got pierced by the spikes o.o
..hey, it just stuck in my head.
Also, jolteon knows Pin Missile, which is one of my favourite moves for some reason.
However, I do like raichu.. and I'm not sure why. I always preferred it to pikachu and was annoyed when it stopped learning attacks after evolution, which is very rude of it. Actually that annoys me about most stone-evolving pokémon. I was most thrilled when I found out that the eeveelutions didn't follow this pattern so.. so that's another plus for jolteon there o.o