@DrewDad,
That "Enternal Sunshine" isn't sci-fi? It could be placed in a romance category but the central premise would make that comparison ridiculous.
Sure, this list is based on what reviews could still be assembled so it is, at best, an estimation.
AFI's list which includes film critics, but also script writers, directors, film historians, producers, actors, others in the industry as well as the general membership is almost entirely different:
1. 2001: A SPACE ODYSSEY 1968
2. STAR WARS: EPISODE IV - A NEW HOPE 1977
3. E.T. - THE EXTRA TERRESTRIAL 1982
4. A CLOCKWORK ORANGE 1971
5. THE DAY THE EARTH STOOD STILL 1951
6. BLADE RUNNER 1982
7. ALIEN 1979
8. TERMINATOR 2: JUDGMENT DAY 1991
9. INVASION OF THE BODY SNATCHERS 1956
10. BACK TO THE FUTURE 1985
Except for "Star Wars - A New Hope" which should have been "Star Wars - The Empire Strikes Back", Spielberg's "Close Encounters of the Third Kind" for "ET," "Aliens" for "Alien", it seems more credible. Where will the new resounding critical success of "Star Trek" fit in? Only "The Wrath of Khan" or "First Contact" get really good critical marks out of that entire franchise. There's a sweet sentimentality to "ET" remaining at the top, but it borrows heavily from fantasy and the only science is the makeshift communications device and the final globular space ship (which I hated) -- ET rescued by a giant armored basket ball?
BTW, has anyone seen "The Host?" Its' sample footage is on YouTube and is a Korean monster movie which is actually quite well done -- the Asian version of "Jaws."