I'll second John Carter. It wasn't that bad of a movie, the studio just decided to cut their losses before it even released and didn't market it. It was also weird that they changed the title late in development.
Bad movies I liked? Both Arnold Conan movies (Conan the Barbarian got horrible reviews from many in the community, including a scathing review in Dragon magazine).
Kung Pow. Yep. I like that movie. Deal with it.
Enemy Mine
Related, revered movies I don't like? Big Lebowski and Dune.