Jolteon is definitely the best choice outta those, in my opinion. But I think they're all great n' got their own advantages in one way or another! Sylveon's really cool, too, but you already said you got a Fairy type.

[Jolteon and Sylveon are the only two Eveelutions Jimmy actually owns, but he does like them a lot.]

But I think it's really best to let your Eevee decide! Solstice had a bit of a hard time picking what she wanted to be, but the wait was worth it. She's really happy with what she is, now.