Wow - lots of surprising responses here. I prefer metal, here is a small sampling of what I regularly listen to and the genres. (I can't stand most rap and emo)
Hardcore & Hardcore mixed with metal:
Pantera
Hatebreed
Dry Kill Logic
Killswitch Engage
Shadows Fall
In Flames
Thought rock:
Dream Theater (just saw them film a DVD in NYC)
Tool
APC
Yes
King Crimson
King's X (Probably my all time favorite)
Pink Floyd
Beer drinkin' metal:
Black Sabbath
Ozzy (up through no more tears)
Black Label Society
Dirty Rig www.dirtyrig.com
AC/DC
Brand New Sin
80's metal:
Dio
Dokken
Badlands
Motley Crue
Van Halen
GnR (Appetite)
Acoustic/Classic Rock:
Crosby Stills Nash & Young
Simon & Garfunkel
Cream
Journey
The list goes on, I love music and listen to some newer stuff like Franz Ferdinand, Disturbed, and I can't forget to mention The Cult.
I have several thousand CDs, too hard to list. Thank God for iPods.