But films like Rollerball, Flash Gordon, They Live!, Robocop, etc. are all pretty silly. Entertaining but not technically better or worse than The Fifth Element (and, actually, probably technically worse) I've heard people try to argue that Sky Captain and the World of Tomorrow is a classic while Ebert just called Knowing one of the best sci-fi films ever made.

You might be able to get a Top 20 that most people can agree upon but 20 - 25 will probably be all over the place.