Overall, classical. It's the only genre I've enjoyed from childhood to middle age and I still love the same compositions I did 30 years ago, but I've also gotten into 20th century and came around on baroque. I like pretty much all of it these days. It also plays well with my favorite headphones and speakers, vacuum tubes, and there's a ton of it on SACD. Great recordings abound.
I'm also a big jazz fan, but came late to that party. I've only been into it for five years. I wish more was available in hi-rez and that collectors hadn't squirreled away most of the good vinyl while driving up prices.
I also love rock (oldies, classic, punk, psychedelic, classic metal, New Wave, grunge, alternative, indie), country (including bluegrass, folk, classic country, alt.country/No Depression), world music, a little gospel, a little electronica, and a few oddballs that don't fit anywhere. I have a handful of early rap records - back when new ground was being broken - but the genre has disappointed me for the past 20 years.
I don't have an ear for most commercial music, either. Commercial rap/hiphop, pop, country, et al. don't have anything that interests me. The contemporary music I like falls into small niches, while a lot of older popular music has a lot of appeal. It's hard to believe that something like "Take Five" was a hit with broad appeal at one time. I'm also horribly jealous of my parents who got to see Dave Brubeck play at a small bar in Redondo Beach. (Though not complaining too much - I've seen plenty of wonderful performances.)