Source comes from Cinescape (Jan/Feb 1997), which is posted in USENET rec.arts.sf.movies newgroup.

The 20 Most Influential SF Movies Of All Time (in order)

  1. 2001: A Space Odyssey (1968)
  2. Star Wars (1977)
  3. Blade Runner (1982)
  4. Metropolis (1986)
  5. The Terminator (1984)
  6. Terminator 2: Judgment Day (1991)
  7. Alien (1979)
  8. The Day the Earth Stood Still (1951)
  9. Le Voyage dans la Lune (1903)
  10. Invasion of the Body Snatchers (1956)
  11. Things To Come (1936)
  12. A Clockwork Orange (1971)
  13. Close Encounters of the Third Kind (1977)
  14. The Thing (1951)
  15. Mad Max 2 (1981)
  16. Planet of the Apes (1968)
  17. Aliens (1986)
  18. The Andromeda Strain (1970)
  19. Forbidden Planet (1956)
  20. War of the Worlds (1953)