Metropolis
This was a tad bit long for my liking but Brigitte Helm literally served. Like as the machine man she's comical and eccentric and as Maria she is poignant and sweet. The sets too are out of the world. It's really incredible. And the special effects too are just incredible. Fritz Lang is a really good director.
I don't know if I'd ever watch it again (I probably will) but it's a really compelling film and definitely a contender for the best silent (and German) film ever.