Let's compare the two:
Amazing Sp. Atk and Sp. Def
Useful ability (Volt Absorb)
Outspeeds pretty much everything
Learns moves like Discharge, Thunderbolt etc.
You can get an Eevee pretty early
Access to Signal Beam, which counters Dark and Psychic types.
Only one weakness - Ground
Learns good moves late
You'll need a Heart Scale to make it remember T-Shock, its first Electric move
Good Atk. and Sp. Atk
Access to Wood Hammer, an amazing STAB move
4x Weak to Fire
Weak to a lot of types (7)
Evolves pretty late (Lv. 40)
It's ability (Snow Warning) may hurt the rest of your team
You should go with Jolteon
It's a much better counter to Water-types, but also a little frail physically so be careful!
Jolteon @ Anything
- Signal Beam
However, if you still want an Ice-type to be on your team, go with either Glaceon or Weavile
Glaceon @ Anything
- Ice Beam
Glaceon is a bit shallow in terms of movepool. It's only good STAB moves are Ice Beam and Blizzard. Weavile is also an option. She's notorious for being very frail, but since she outspeeds pretty much everything - supported by the massive Atk. stat as well - that shouldn't be a big trouble. You can get a Razor Claw to evolve Sneasel pretty early in Cyrus' room in the Veilstone Galactic building via the Dowsing MCHN.
Weavile @ Anything
- Ice Punch
- Night Slash
NB: Ice Punch can be learned through the Move Tutor in Route 212 under the cost of 6 Blue Shards and 2 Red Shards. Night Slash can be learned through the Move Reminder in Pastoria city under the cost of 1 Heart Scale.
Hope I helped!