I don't have a favourite movie.
I either enjoyed watching what I just saw or I did not. I only remember movies I've enjoyed in the past if they come up in conversation, otherwise I don't commit such things to top-level memory.
I have never understood why some people have DVD/Blu-ray collections of movies they enjoyed when they first saw them. Part of the thrill and enjoyment of a good story is in being 'surprised' by plots/twists and the unexpected. I rarely watch anything for a second time.. Movies I've downloaded from the web (sssh, don't tell!) are deleted after I watch them.
I enjoy looking forward to something new, fresh and the unkown.
I know, probably a shallow boring old phart..