Started out with Black Sabbath and King Diamond When I was 8, then found Judas Priest and Iron Maiden. Then Slayer (still listening), Anthrax (stopped when Joey left but am listening now that he's back), Metallica (stopped after ...And Justice for All), Megadeth (stopped after Countdown to Extinction). Not sure you'd call System of a Down "metal" (more like heavy punk) but regularly listen to them as well. Also like Lacuna Coil, My Chemical Romance, Sepultura, Death Angel, anything with good riffs and vocals. Given a choice, I'll always go for Speed or Thrash metal.