What's your favorite movie made before 1950?

So far, my favorite has been Casablanca, though I saw Mrs. Miniver recently and I found that to be a fantastic call to arms with emptional depth.

I suspect that Citizen Kane and The Wizard of Oz will garner a lot of praise (along with films I've never heard of), so I'm genuinely curious about your selections.

You're more than welcome to argue the semantics of "the best" versus "your favorite". Either way, I am eager to watch your picks where possible!