Classic science fiction movies versus modern science fiction movies should not be done considering the advancement of special effects.
The Day The Earth Stood Still receives my vote for the best classic science fiction film that is on the list.
Blade Runner would be my choice for best modern science fiction film.
I always considered
Alien a mixed genre that crossed horror over into the science fiction realm.
Also, the orginal
Dune is a good science fiction film to watch too
