Seeing some great bands in here: Tool, Testament, Faith No More, Nightwish, Mary Beats Jane (quite surprised to see that one in here)
As for me, I can't just pick one band. In addition to the bands listed above, I like Amorphis, Iced Earth, Samael, OLD In Flames, Dark Tranquillity, Green Carnation, Orphaned Land, Paradise Lost, etc.