Citizen Kane
Citizen Kane is one of the most respected movies ever made, and I was still surprised by how much I liked it.
The combination of quality, influence, and the fact that it was essentially entirely made by Orson Welles alone is truly baffling. It is one of the best edited and sequenced movies I have ever seen, the camera work is interesting, and blends some of the greatest styles together into a mixture that is arguably better than all of its components. The story is somewhat bizarre but has aged incredibly, especially the ending. Can't really put a lot of it into words. You have to just watch it. It is Citizen Kane.