It's impossible to quantify the best drummer of all time, it's pointless to even try. To do so just makes the people in the argument look stupid. Just like athletes, they all have to be judged by era as musicians and athletes both evolve at staggering paces on a yearly basis. Buddy Rich, Gene Krupa, Louie Bellson, Keith Moon, Billy Cobham, Tony Williams, John Bonham, all great and amazing drummers, but drummers like Dennis Chambers and Neil Peart took the foundation they laid, ran with it and created a name for themselves by taking all of those previous fundamentals to a new level. Rush is my favorite band and Peart is my favorite drummer, but I absoloutely recognize that even Neil's talent has been improved upon tenfold. There are guys out there like Mike Mangini, Bobby Jarzombek, Thomas Lang, Marco Minnemann, Matt Gartska, Alex Rudinger, and so many others in the extreme metal genre I haven't even bothered naming that leave all the previous mentioned names in the dust. There are drummers today doing things on a kit that the founding fathers would have NEVER thought possible. As a drummer myself, I find it much more productive and rewarding to discuss the amazing contributions all these names have provided for our listening pleasure rather than pit them against one another for the "best drummer ever" title, because in the end it's an absolutely pointless argument that will never have a clear cut winner.