Good sci-fi movies:

• Predator
• Terminator series (2nd and 1st part are good),
• Aliens (1, 2, other acceptable),
• Primer (time travel),
• Prestige
• Batman Begins (and others)
• Interstellar
• Star Wars
• Back to the Future
• Inception
• Ghost in the Shell
• Planet of the Apes (all parts are good, so I heard)
• Matrix
• Gattaca
• The Thing (sci-fi horror, 198?)
• Contact
• The Fifth Element
• Minority Report
• Avatar
• Total Recall (1990)
• Robocop 1, 2
• Class of 1999 (B class movie, but fun)
• Moon
• Altered States (horror)
• Tron
• Howard the Duck (B class movie, fun)
• Spaceballs
• Intercosmos
• The Fly (horror)
• The Abyss
• Honey I Shrunk the Kids (~)
• Jurassic Park (1993, other parts are good as well)
• Demolition Man
• Stargate
• Lawnmower Man
• Cube
• Man in Black
• The Truman Show
• Artificial Intelligence: AI (acceptable)
• I, Robot
• District 9
• Apollo 13 (more like documentary)
• John Carter
• Judge Dredd
• Iron Sky
• X-Men (some parts)

Other interesting:

• ???