Well I've been a drummer since I was a teen, and I have a few picks. Of course there are many excellent to great drummers, it just depends I suppose on the mood you're in that day or the music you like best. Too many to list really.

I'd say there is no "best" drummer. They all bring their own thing to the table. Some are more "technical", some are better groove or "pocket" players, some are great composers/arrangers of percussion, some don't overwhelm you but play for the tune and if they weren't there it wouldn't sound right, etc.

For rock, some mentioned above I would agree with are Martin Chambers (Pretenders), Capaldi (Traffic), Bonham, Bruford, Charlie Watts, Ringo; also Matt Abts (Gov't Mule), Nick Mason, Barriemore Barlow (Tull), and so on. Quite a few to like in rock.

Guys like Michael Shrieve, Bruford, Vinnie Colaiuta can be considered rock or jazz really - all in the "great" category I would say. Then you have guys like Graham Lear, Rodney Holmes, Gavin Harrison, and Marco Minnemann that don't get enough mention.

Jazz or funk/fusion drummers I like are Art Blakey, Max Roach, Bill Bruford, Roy Haynes, Sonny Paine, Bernard Purdie, Vinnie Colaiuta, Jack DeJohnette, Billy Cobham, David Garibaldi.

If you don't mind hard rock/metal, check out Danny Carey of TOOL. He's excellent, and not your typical "metal" drummer. I'd recommend the album "Lateralus" or "10,000 Days". TOOL is something of an acquired taste maybe, but Carey is one of the most talented drummers in the world right now.