Apocalypse Now. I think out of all the films I've watched more than once this one has had the most repeated viewings. Mythmaking like most war movies but took it on its own path. No Vietnam movie made after it lives up, IMHO, regardless of it being more historically accurate. Apocalypse is about truths other than literal history. That's why I can never tire of it.
The Eye. Begins as a cover version of the Sixth Sense but outclasses it and drives well beyond its initial premise to reveal a tale of punished difference. Some of the creepiest ghosts on film.
Network. Unbelievably witty dialogue only enhances this satirical fable from the 70s. Every gag still works.
Yojimbo. Gun for hire samurai film is the mid point between Kurosawa's John Ford influences which led to Sergio Leone's Kurosawa influences which then led to the new Western back in America. The samurai film was changed forever with this one.
Masculin/Feminin: Godard mid-turn from cine revolutionary to revolutionary cineaste. His Revolver album (released same year): before it it was fun, after it it was war.
Werckmeister Harmonies: Bela Tarr's masterpiece towers over the rest of his output for its break into warmth and humour to add to the usual closely studied misery. Like a cinema verite folk tale in modern dress.
Eraserhead: When someone makes a film that gets to me more than this one I'll put that title in place of this one. Doubt it'll happen, though.
Martin: Is Martin a vampire or just playing? If he is a vampire, however old he is, he's still a mixed up teen. Extraordinary idea kept under Romero's tough grip. Works.
Suicide Circle/Suicide Club: First it's a J horror. Then it's a police procedural. Then it's a kind of creepy teen film. Suddenly it's a Ken Russell musical. Then it's like Kubrick on acid.
Audition: Masterpiece from one of the most prolific filmmakers on the planet, Takeshi Miike. Extraordinary tale of what might lie beneath beauty, poise and appeal. The twist keeps twisting. No one is innocent. No one gets off lightly.