I'm in the same boat. When you have Ween, Scott Joplin, and Pantera in your music collection, where do you vote? My family has several musicians who play different styles of music, so I grew up loving everything.
I'm voting rock, though, since that's most of what I have. The best CD I've bought in the past year, though? Befriended, by The Innocence Mission. Probably classified somewhere between "alternative" and "folk". My wife found it and I didn't want to buy it at first, but no music has made me as happy as that one CD.