[This is a never-ending project so it's never too late to chime in or update your choice.]
It's simple: Post your #1 ever (no runners-up or ties please) in the comments and I'll add it or I'll add your name to the film if it's already in the list. Please share your story about why it's your choice too if you'd like - I think #1s usually go beyond saying the acting, writing, visuals, music, etc, are perfect. It's deeply personal. Let us know when you saw it, your first reaction, how many times you've seen it, when you made it your #1, and so on.
If you're the type to separate best and favorite, go for the latter.