And for those who prefer more cerebral fare, may I put forth
Enemy Mine, starring Dennis Quaid and Lois Gosset Jr.
While most certainly Sci-fi, it is also an interesting example of how people from mutually-hostile cultures can co-operate when required, even to the point of actually becoming friends.
For those who like Star Wars (or at least, Star Wars before Disney grabbed it and decided to unleash Rian Johnson on it), the fan-films
Darth Maul: Apprentice and
TIE Fighter: Short Movie will be diverting as examples of what could have been...
For a so-bad-it's-
awesome film, you cannot beat
Flash Gordon. The kitschy costumes and sets are more camp than a field of Scouts, they had to over-dub every single thing the lead actor said and the plot has holes in it that you could fly War Rocket Ajax through with ease.
On the other hand, Brian Blessed is obviously having the time of his life as VULTAN! KING OF THE HAWKMEN! while the music by Queen cannot be bettered.
Switching to non-sci-fi, the Rutger Hauer film
Blind Fury is a kind of guilty pleasure, being effectively a modern re-do of Zaitochi. Seeing a blind swordsman take down an entire criminal syndicate during a rescue mission never gets old...