Choosing one favorite movie is impossible. I am influenced by many factors when choosing favorite movies:
Genre
Mood
Timing
Weather
For example, if I am in a happy mood, then my favorite movie selection might be Modern Times, The Patsy, Holiday, Forty Second street, or one of a doze Temple movies, like Little Miss Marker.
If I am in a darker mood, I would be choosing somthing like On Borrowed Time, Strange Cargo, The Big Street, Baby Face, or Death Takes a Holiday.
If I am in an introspective mood, I would be choosing something like the silent classic The Crowd, or The Big Parade, Design for Living, or maybe Captain's Courageous.
If I am in a vengeful mood, something like The Women, Rain, The Unholy three, West of Zanzibar, Now Voyager, or Blonde Crazy would be selected.
You see? It's impossible to have to select just one.
"My dreams, watching me said, one to the other...this life has let us down."