Kagemusha would probably be my choice.
It's a samurai epic by Akira Kurosawa, and the first epic that he was able to film in colour. It's been overlooked somewhat, in contrast to many of his other films, probably because it was slightly overshadowed by Ran, which followed about five years later. It took Kurosawa a very long time to get funding for this film, so while he was looking for money he painted over 200 scenes to use as storyboards. It shows in the finished product: it's a gorgeous film. Tatsuya Nakadai is wonderful in the lead role, and the final battle sequence is stunning precisely because the audience doesn't actually see any of it; you only have the expressions of the commanders to tell you what's happening.