It all depends on you. there are lot's of great Electric-types to choose from.

If you want power, Pokemon like Elekid, Tynamo or Shinx are good choices when they evolve into their final forms, they're really powerful.

For speed, Helioptile, Blitzle, and Electrike are good. they're real speed freaks.

For movesets, Mareep, Joltik, Chinchou and Rotom. Rotom is especially good because of it's forme changes.