Everyone has a movie that they love above all overs (and one they hate above all others).
Me personally, my favourite film is either Lord of the Rings (it counts as one if you watch them all together!) or Hot Fuzz. It's probably Hot Fuzz, actually. No other movie have I been able to watch several dozen times and still smile at it.
As for worse... Watching The Human Centipede when eating dinner wasn't all too pleasant.