1. Sean Reinert (Death, Cynic, Aghora)
2. Bobby Jarzombek (Spastic Ink, Riot, Halford)
3. Asgeir Mickelson (Spiral Architect, Borknagar, and a billion others)
4. Brann Dailor (Lethargy, Today is the Day, Mastodon)
5. Dave Lombardo (Slayer, Grip Inc, various guest appearances)
6. Gene Hoglan (Death, Dark Angel, SYL, etc)
7. Davide Piovesan (Ephel Duath)
8. Greg Hall (Sacred Reich)
9. Charlie Benante (Anthrax, SOD)
10. Alex Arellano (Power of Omens)
Since he said metal drummers I couldn't include Neil Peart or Tim Alexander, even though both have been semi-metallic at times.
Edit: I can't believe I forgot Brann Dailor!! Fixed.