Sounds like you go for the cerebral sci fi films like me OP. Here’s some of my favourite oldies;
2001 (slow burner but still one of the best sci fi films ever made)
Solaris (the original Russian film by Andrei Tarkovsky)
Stalker (again by Andrei Tarkovsky)
Akira (Japanese animation, watched the new Blu Ray version this week and it blew me away how this hasn’t aged at all considering its nearly years old).
Blade Runner (probably seen it many times but the Final Cut Blu Ray picture looks stunning).
Pi (Darren Aranovsky, I think it was either his first film or one of them)
Eraserhead (David Lynch at his finest)
Videodrome (David Cronenberg’s critique of mass media)
While we’re on the subject of Cronenberg, Shinya Tsukamoto’s Tetsuo: The Iron Man has always been one of my favourites. An oldie but a goodie.