Blade Runner (1982)
A classic among classics. Probably my second favorite science fiction film right behind 2001: A Space Odyssey. This movie does everything right. Everything, every single detail of this film, is fully developed and realized. One thing this film does that a lot of typical sci-fi fail to do is make the technology just another detail of the setting. The characters don’t gloss over new weapons or gadgets because why would they? They’re used to it just like we’re used to seeing iphones and androids on the street. Another film that comes to mind that does this is Children of Men (probably my third favorite sci-fi film).
If you haven’t seen this film, you should add it to your list right now. There are a bunch of versions of it floating around out there (because of studio interferences, there’s a whole history behind it blah blah blah), but if you can find the Final Cut version, that is the version to watch (followed by the 1992 director’s cut).