[(-) Ions]

Then - Bill Ward. I also think (although not a metal drummer) Mitch Mitchell also deserves a mention here.

Now - Either Mike Portnoy or Danny Carey. Mike is a spectactualr technical drummer, who uses some of the most unusual time signatures I've ever heard - Listen to Dream Theater's "The Dance Of Eternity" to see. Danny is one of the few drummers around who actually uses his drumkit as an instrument as opposed to just percussion or timekeeping - Tool's "Schism" in which him and bass player Justin both play the main riff is a good example of this.