I like Bluegrass too. My first inclination was for Country, because I often like sing-along-y kinda stuff, but I think Bluegrass is more "musical" / less "pop".
Really, tho, I like any well-done music. Have gone through big Mozart / Classical / Opera phases, Jazz phase, Country.... Hip Hop, Show tunes ~ lots of stuff.
But I keep coming back to Rock & Roll... I expect I'll be rockin' out in my rocking chair when I'm a little old grey-haired lady... (like now) ;-P lol
**and then I read everyone else's answers**
How could I forget the Blues?? I love the Blues...