I was originally going to title this post My Three Favorite Sci Fi Films, but I could not settle on just three films. Picking the first two wasn’t all that tough for me. 2001: A Space Odyssey and Blade Runner always stand out in my mind as the two best Science Fiction films ever made. Maybe I should have designated them 1A and 1B. Picking films for the 3 to 10 positions is more challenging for me because I can think of quite a few Sci Fi’s that I think are very good, but just not as good as 1 & 2. There are probably about 20 films I considered for positions 3 to 10, but the films I listed below are the ones that made my final cut, although a few of those might change if I had to draw up this list again in 6 months or a year.
1) 2001: A Space Odyssey
This 1960’s classic is not only my favorite sci fi film, but one of my favorite films of any kind. A fascinating film that explored man’s evolution, the advance of technology and the concept of a supreme intelligence in the universe. One of Stanley Kubrick’s finest, which is saying quite a bit, since all his films were good and some were outright masterpieces.
2) Blade Runner
The rest of my top ten in no particular order:
The Empire Strikes Back
My favorite of the Star Wars films.
Twelve Monkeys
Dune
The Planet of the Apes
Aliens
The Matrix
Forbidden Planet
A classic film with an outstanding cast. Special effects which were state of the art at that time and not surpassed until Kubrick’s 2001.
Robocop
The political satire in this film was absolutely brilliant.
I doubt the upcoming remake will match iconic film.
gmf journal 
2001: A Space Odyssey, and Alien definitely top my list, and the others you mentions are some of my favorites too.