There are no genres of music that there isn't at least something I'll listen to.
But generally my favorites are Indie, Ska, Acapella, and Folk. Artists such as Spoon, Beirut, Fleet Foxes, The Mighty Mighty Bosstones, Rockapella, Four Guys Standing Around Singing, Bob Dylan, Steve Earle, Robbie Fulks. Those are generally my favorites.
I'll try just about every genre of music but I'm extremely picky about it in general. I mostly listen to power metal, southern rock, trance and techno (Aphex Twin and Darude own), with some classical in there, the truly epic-sounding orchestral scores only.
When I'm riding with friends and they listen to Weezy or whoever they're told to like this month I feel like stabbing my eardrums with an awl. There is one exception, the only rapper I like; Necro. His stuff is practically half metal, and ALWAYS unrelentingly brutal and morbid, so be warned. Runs his own label too.
Edit: Anyone know of any good instrumental Arabic or Japanese music? I think I'd like it but I don't know where to start.
Mostly metal. But anything good for the moment. I have no problems with music if the rest is ok, have a completely full activated system of disconnecting music mode when I don´t like it and when I am alone I play what I like.
Worst is that sometimes I get hooked on some songs for days...