Akira
I have heard plenty about this movie before watching it. Everything I've read and watched has praised this, all of my favorite movies seem to be in the same discussion. I figured this was because it was a great movie, of course, but also that all the influences are under my taste, and therefore I'm just more likely to think highly of Akira.
Even among all of that, I was impressed. Every couple of minutes there was something some other movie, or maybe multiple movies, had done. Sometimes stylistic or aesthetic choices, blatantly copying shots, taking great influence in the story. This is a great movie for a lot of reasons on its own, but the one thing I wanted to highlight that.
This is a movie that is made up of a thousand movies holding it up in praise, I think that's pretty cool.