Metal for me is mostly underground. Bands that you won't see on MTV or hear on the radio. Stuff like 6 feet under, Arch Enemy, Marduk, a bit of Cradle of Filth, Cannibal Corpse (Chris Barnes years), Devil Driver, and Hatebreed just to name a few.
The more mainstream stuff for me would be, above all else Disturbed. Then Linkin Park, Static-X, Breaking Benjamin, and a hell of a lot of 80's rock. It's what I grew up on and I still love it. I mean who from that area doesn't remember Cherry Pie? Warrant was awesome, especially some of their ballads. I'm a sucker for slow songs.