Though your list is quite impressive, its very lacking. You should never list bands like Disturbed, Korn, and Drowning Pool with the true heroes of metal like AC/DC and Black Sabbath. Also, you're missing some of the key founders of the whole metal genre and some great pioneers of rock. As it is though, I voted for Black Sabbath, because as far as that list goes, they did the most for music and revolutionized it, making the way for bands like Metallica and AC/DC.
And why is Nickelback even listed?