I dont think the Slipknot drummer is that great. He just does the job pretty good thats all.
Ill have to go with Hellhammer like yourdeadgroom said.
Hes not my favorite, but hes simply the best. His skills are amazing and hes extremely fast. Hes the only one in Mayhem who shows real talent.
Gene Hoglan is one the best yes. Though he said himself that he stole a drumming style from someone else in 'Individual Thought Patterns. Hes still fucking great.
Dave Lombardo (Slayer), Pete Sandoval (Morbid Angel), Flo Mounier (Cryptopsy), Trym (Emperor), Vinnie Paul (Pantera), Sein Reinert (Cynic) are amongst the best in metal, along with....
Nick Barker. Hes my favorite. Maybe because CoF were one of the 1st extreme metal band i listened too. Hes not the best, but he has the best style. Just too good.