Hmm... depends on my mood. Bands I like almost any time include Zeppelin, Pink Floyd, Rush, Foo Fighters, and old (pre-And Justice For All) Metallica. I usually go through periods where I get really into a genre of music (rock or punk specifically) and don't listen to much else. Right now I'm on a ska kick and and listening to a lot of Reel Big Fish, The Mighty Mighty Bosstones, Streetlight Manifesto, and Big D and the Kids Table. At various other times I've listened to a lot of: Ramones, The Clash, The Cure, Daft Punk, AC/DC, Hendrix, The Who, Bob Seger, Cake, Arlo Guthrie, The Cars, Misfits, Dead Kennedys, Face to Face, NOFX, Less Than Jake, The Offspring, Judas Priest, Iron Maiden, Queen, and Jimmy Buffett. You can even catch me listening to blues, bluegrass, or classical music from time to time.
There is very little music I'm not open to listening to but I have yet to find any country or rap/hip-hop that is of any interest to me.
And contrary to a previous poster, if I can track down a copy of an album I prefer to listen to it all the way through. Sure, sometimes I like the convenience of just picking my favorite song, but I would never have discovered my favorite PF song (One of These Days, BTW) if I just listened to the popular tracks/albums.
How about bands that you hate? Me, I wish Nickelback would crash into a mountain. And don't get me started on Creed reuniting. Ugh, I can't even come up with words to sufficiently describe the level of loathing I have for their "music."