I love AUs. All of my fanfic is AUs, mostly of the *insert character here* survives what killed them in canon/comes back from the dead AUs. Way too many characters I love get killed in canon.

I love What If AUs, Fantasy AUs, Modern Day AUs, Modern Fantasy AUs, Sci Fi AUs, pretty much any AU.

The only kinds I can think I don't like are the Dark, or Slytherin Harry fics in Harry Potter, and things like that. I've never come across one that hasn't horribly warped some, if not all the people who loved Harry in canon.