Here's what everyone else in the world think on this topic:
http://www.imdb.com/chart/scifi
Best Science Fiction Movies
Rank Rating Title Votes
1. 8.7 Star Wars (1977) 120,508
2. 8.7 Star Wars: Episode V - The Empire Strikes Back (1980) 92,733
3. 8.7 Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb (1964) 55,881
4. 8.5 Eternal Sunshine of the Spotless Mind (2004) 23,533
5. 8.4 Matrix, The (1999) 127,757
6. 8.3 Metropolis (1927) 10,378
7. 8.3 Alien (1979) 56,069
8. 8.2 2001: A Space Odyssey (1968) 58,585
9. 8.2 Clockwork Orange, A (1971) 57,301
10. 8.2 Aliens (1986) 57,294
11. 8.2 Donnie Darko (2001) 39,386
12. 8.1 Blade Runner (1982) 67,663
13. 8.1 Terminator 2: Judgment Day (1991) 69,280
14. 8.1 Bride of Frankenstein (1935) 3,990
15. 8.0 Day the Earth Stood Still, The (1951) 9,025
16. 8.0 Star Wars: Episode VI - Return of the Jedi (1983) 73,203
17. 8.0 Young Frankenstein (1974) 19,716
18. 8.0 Back to the Future (1985) 60,761
19. 7.9 King Kong (1933) 8,987
20. 7.9 Brazil (1985) 27,388
21. 7.9 Frankenstein (1931) 5,222
22. 7.9 Twelve Monkeys (1995) 55,560
23. 7.9 Terminator, The (1984) 53,168
24. 7.8 Invasion of the Body Snatchers (1956) 4,600
25. 7.8 Planet of the Apes (1968) 18,195
26. 7.8 X2 (2003) 31,791
27. 7.8 Spider-Man 2 (2004) 27,789
28. 7.8 Fail-Safe (1964) 2,841
29. 7.8 Iron Giant, The (1999) 13,207
30. 7.8 Thing, The (1982) 14,692
31. 7.7 Minority Report (2002) 44,808
32. 7.7 Close Encounters of the Third Kind (1977) 24,056
33. 7.7 E.T. the Extra-Terrestrial (1982) 39,925
34. 7.7 Abre los ojos (1997) 6,850
35. 7.7 Lost Horizon (1937) 1,865
36. 7.7 Delicatessen (1991) 10,093
37. 7.7 Invisible Man, The (1933) 2,157
38. 7.7 Kaze no tani no Naushika (1984) 2,392
39. 7.7 Truman Show, The (1998) 56,247
40. 7.6 Cité des enfants perdus, La (1995) 9,634
41. 7.6 Shin seiki Evangelion Gekijô-ban: Air/Magokoro wo, kimi ni (1997) 1,436
42. 7.6 Solyaris (1972) 4,506
43. 7.6 Forbidden Planet (1956) 6,099
44. 7.6 Akira (1988) 12,962
45. 7.6 Incredible Shrinking Man, The (1957) 1,390
46. 7.6 Night of the Living Dead (1968) 9,916
47. 7.5 Kôkaku kidôtai (1995) 7,995
48. 7.5 Man in the White Suit, The (1951) 1,080
49. 7.5 Equilibrium (2002) 13,850
50. 7.5 Seconds (1966) 1,518
GATTACA barely missed the top 50, it has a 7.5 rating (must have a lower hundreth value than Seconds).