I love sci-fi movies. There's the ones that are just fun to watch and re-watch based on good imagery, action, and story - stuff like Mad Max Fury Road, pretty much anything from James Cameron, Fifth Element, etc.
But because I dissed Ex Machina, here are some of the more "thoughtful" sci-fi movies I really enjoyed.
Gattaca
Moon
These Final Hours
Children of Men
The Road
12 Monkeys
2001
Brazil