1: Alien (probably not surprising)
2: The Matrix
3: Predator
4: Return of the Jedi
5: The Terminator
I feel kind of shallow, preferring spectacle and visuals over most everything else (and also nostalgia), but hey, that's what the escape of the medium is primarily for me.
Honorable mentions: Back To the Future, Blade Runner, Castaway, Cube, The Dark City, Gremlins, Groundhog Day, Jaws, Jurassic Park, The Karate Kid, Lord of the Rings, Memento, A Nightmare On Elm Street, Starship Troopers. I could see Infinity War/Endgame going up here at some point, I just don't have the same history with it that some did.
Favorites of past decade: Alita: Battle Angel, Annihilation, Enemy, Ex Machina, Interstellar, It Follows, John Wick 3, The Edge of Tomorrow