Tron Legacy is so blaaaaaand. Ugh.
Can't understand calling a fun movie like the original bad while praising that dreck of a sequel.
Can't really say I have a favorite bad movie. "Bad" would imply "this is so bad I really shouldn't be enjoying it," but I greatly enjoy the movies I like and don't consider them "bad"—your mind kind of warps when you get into exploitation and low-budget horror territory where bad no longer seems so bad and is simply the norm and even sometimes cool or preferable to big-budget shitty Hollywood styles of filmmaking, acting, etc.
But I dunno... I'm sure there are some "guilty pleasures."
Street Fighter is pretty bad, and I adore it.
Karate Kid III is bad but has its qualities.
Well, I guess there are some movies...
Blood Feast is terrible but is such a spectacle because of the shocking gore (especially considering it was 1963), and I shouldn't enjoy the acting or non-photography in it but I do.
I'm sure there are others.