I can't name a favorite. There are so many great films, so many great writers, directors, producers, actors. I doubt that any single one can be best, since they are all great.
I like many different genres, Westerns, science fiction, war movies, comedies, anything that is done well and has good continuity.
One film that I really like is The Life And Times Of Judge Roy Bean. Like Its A Mad, Mad, Mad, Mad World, the cast is a who's who of the time. Paul Newman, Roddy McDowell, Ned Beatty, Victoria Principle, Jacqueline Bisset, Ava Gardner, Tab Hunter, Stacy Keach, Anthony Perkins.
Bad Bob comes to town.
The boys play poker. Everything is cool until the dude indiscriminately shooting up the Jersey Lily bar shoots the poster of Lily Langtree.
Bean is pretty touchy about Lily Langtree. He has an enormous respect for women. In the next scene he does the right thing and makes a formal apology to the town's 'women folk'.