For my underappreciated:
The Badadook. Fantastic horror movie. Good reviews, but not seen by alot of people.
True Romance is up there. Dennis Hopper's speech when he knows he is going to die is one of my favorite scenes ever.
Sunshine. Really great Sci-fi flick.
Joe Versus the Volcano. Considered one of Tom Hank's worst movies, but it has some great quotes and underappreciated symbolism.