well, i liked Robot Jox. very much so. You won't find that one on anyone's list.
i also liked a lot of 60s, 70s and 80s crap like the Quartermass series, the two Time Machine films.. i find Phase IV to be a stimulating film, but the ending felt incomplete.
The Day After was really moving and scary. It's more of a science drama, though.
I remember as pretty good at the time Spacehunter - Adventures In Excessively Long Titles
http://www.imdb.com/title/tt0086346/reference which has a short-haired, barely dressed Molly Ringwald who was super hot at 15yo (no paedo, i was only 17yo).
oh btw, before i forget - they are making a film version of the comics "Valerian Et Laureline"
http://www.imdb.com/title/tt2239822/reference
I like modern scifi too, like Paycheck, Equilibrium, or late 80s stuff like Total Recall, but i feel that in many modern films which have a strong science aspect(e.g District 9, The Martian), it's not really the driver behind the main feeling;
like, the famous Dark City argument. Yeah, ok they are on a spaceship, but it feels like a horror film, not like scifi. even star wars feels like an adventure movie, it has more in common with Indiana Jones than it does with 2001.
For example, i loved the absolutely awful Silent Running (back home, marketed as "2002 the second odyssey"), and the equally bad Saturn 3. Rollerball, Logan's Run, THX1138, Soylent Green, even the absurd Zardoz will always remain in my memory as great films when i saw them. They have this feeling of unknown, that they are showing you something from the future as "real", whether they mean it to be from *our* future or from a fantastic future.