Neil Peart is in a league of his own. He's still the best in rock music-- there might be others who are faster or louder or who rock harder, but there's no other rock drummer that pushes the limits of the instrument like he does.
My current favorite, and one that hasn't been (and might not otherwise be) listed is Tim Alexander of Primus. I think he's the closest competition that Peart has had. If you doubt it, just listen to 'Sgt. Baker' on 'Sailing the Seas of Cheese.' Like Peart, his playing is already more complex than most people's, and that's even before his fills.
I was surprised to not see Stewart Copeland of the Police listed. He has a unique and instantly recognizable sound-- sort of a jazz/tribal fusion. He's long been one of my favorites.
And I can't pass up any discussion of drummers without bringing up probably one of the most underrated drummers ever-- Ringo Starr. Seriously. Sure, he had pretty much no flash at all, but he was always-- ALWAYS-- entirely and completely in the pocket. To me, he represents the opposite extreme from most of those listed. The fundamental job of a drummer is to lay down the foundation upon which the rest of the song is built, and the foundations that Ringo built were always solid and unobtrusive and utterly flawless. To me, that doesn't imply substantially less skill than someone like Peart-- just a different sort of skill.
And Alex Van Halen really deserves a mention too. He set the standard for double bass metal drummers, and while others have followed that are arguably better (Tommy Lee for example), he led the way.
