I might have said Chris Adler if this was a Metalcore thread :/
Metalcore != Heavy Metal
Anyway, I suppose I should contribute to the thread before the shitstorm commences.
I would say: George Kollias from Nile
Tomás Corn from Lykathea Aflame (Lykathe)
Flo Mounier from Cryptopsy... poor Cryptopsy - their old stuff was so awesome, then they threw it all away for some mainstream success...