This list is thoroughly fluid, and changes a lot for me. So here's my current top three:
3. The Sandman Slim series (Sandman Slim, Kill the Dead, the upcoming Aloha from Hell) by James Kadrey. It's got a premise that seems standard on the surface (guy sent to Hell, tortured, escapes, wants revenge), but the writing crackles with sarcastic wit and crazy-cool dialogue, and the characters are hilariously over-the-top.
2. The Exiles series (Ruins of Ambrai, The Mageborn Traitor) by Melanie Rawn. Magic-wielders in a matriarchal society, revolution, and secret societies. Rawn is a master of alternative sorcery stories, so these novels, her Dragon Prince/Dragon Star trilogies and The Golden Key tie for second.
1. The Hollows novels by Kim Harrison. I love good urban fantasy novels, and this one is wholly believable and beautifully characterized. Anyone who likes GOOD vampire/magic novels should check this out. The style is very similar to the Sandman Slim series.