I like loads of them but my favourites are Metal, Hip Hop and Reggae. The Metal makes me laugh so much.
I know in the base game we only get Salsa, Metal, Techno, R&B, Hip Hop and Pop (can't remember if there are any others). The rest are from expansion packs.
It would be interesting to hear what your favourites are, or what your Sims prefer to listen to.