I can't limit this to just one:
I still enjoy the original Starship Troopers very much. The rest, yuck (can't stand).
I enjoyed the original Star Trek tv series generally, and the movie 'The Wrath of Khan'. I got into 'Star Trek: The Next Generation' as far as an episode entitled 'The Rift' before I realized I could no longer stand Star Trek beyond the original series and the one movie.
'2001: A Space Odyssey' and '2010'. First, a favorite, second enjoyable.
Star Wars episodes I thru VI, and 'Rogue One', all close favorites. Episodes VII thru IX and 'Solo', yuck (can't stand). Never watched the Clone Wars tv series though I keep thinking I might.
Battlestar Galactica, the original series, pt 1 and 2 of the beginning, and the two part episode with Lloyd Bridges and the battlestar Pegasus.
The series 'Firefly' all the way, including the movie 'Serenity.' I just have to ignore the system setting and force move the setting in my watching it, my imagining of it, from a single solar system to a small star cluster.
The oldie but goodie, 'Forbidden Planet.'
My wife loves 'The Expanse'. Me, ehh, so, so.
Not a lot of good stuff out there, that I know of, these days. Walt Disney did a made for tv animated show on the future of space exploration and expansion into space, humans, ships and stations, back in the late 50s or early 60s. It was quite good. Why doesn't some studio and production company update such an animated (or 3D CGI) documentary type film (which would essentially be a movie with us in beginning and in expansion in space? The story line just like in the Walt Disney production, updated to the 21st Century, with a vision of all kinds of space facilities, spin-gravitied ring stations, torus and cylinder in-space colonies (cities, farms, fisheries, forestries, industrial, ship building) in Lagrange space and the asteroid belt, and beyond to the orbits of the outer planets (as well as in to orbit Venus). And, of course, imagining colonies on the surface of Mars supported by facilities in orbit of Mars (connecting via ships and lanes to the rest of a growing, expanding, in-space [beginning] network activity). Really let a world of people know about a titanic possible future out there (about what is POSSIBLE). The SOONER titanic future inside the solar system, not some later interstellar possibility.
'The Expanse' will obviously not be our future in the solar system. It may be good fantasizing, but it's not good vision. With the animation technology we have now, someone should follow Walt Disney's lead and do a movie documentary film of awesome futuristic display. It wouldn't need live actors, or even any voicing, at all. Simply some fantastic accompanying, moving, music. Everything, except the music audio, could be done with deeply well worked [strong], [powerful], animated visuals. Last, but not least, it might put this world on futuristic display with that ever growing potential migration from it to where the action is. The Old World didn't die with the expansionary frontiers of the New World. It died, yes, itself becoming a New World alongside the other New World, as part of [the] New World. Why not such a futuristic documentary movie!? Now that would be a movie for a whole world to watch and dream!