I'm a big fan of Zap as he has a very useful sliding feature along a wet trail he leaves that can be electrified by shooting at it, thus damaging enemies that touch it and actually forming a barrier or trapping some enemies. This means he can move quickly and damage small enemies very easily. He's not a particularly hard hitter so boss battles can be hard work, but his speed makes him hard to hit. Additionally, if you get the soul gem, he regains health in water, which is VERY useful. He's pretty much my default Skylander and the series 2 Zap in Giants is even better as the water slide can be electrified automatically. Sadly he's been dropped from the line-up for for Swap Force, (though of course he'll work in Swap Force) but hopefully he'll be back in a new series 3 form in a later installment.