this shouldn't be a surprise: in the 70's, it was Black Sabbath, the 80's, Slayer, 90's, Pantera, and in the 2000's, Id say either Lamb of God or Slipknot. These bands ruled the decades as far as I'm concerned, although LOG "ruling" is a far cry, but they're excellent. And when I say ruled the decades, I mean they've left a metal legacy that will never be forgotten. Who's on top now though??