I'd have to go with Electric too. It's a tough call between Electric, Psychic and Fire, but Jolteon is my favourite Pokémon and I generally prefer Electric-type moves in the games. They're just cool.
I always pick the Fire-type starter in the games, but if there was an Electric-type I'd probably pick that instead. They've been making some interesting changes in the more recent games, it'd be nice to have more options to pick from when you choose a Pokémon, especially considering how many Pokémon there are at this point.