Named greatest sci fi film of all time

My choice would be Quatermass and the Pit. :cool:
Probably Blade runner. Must watch the film at least 50 times per year. Too many good films of the genre to list but Forbidden Planet, 2001, This Island Earth and The Day the Earth Stood Still are also particular favourites.
For those cerebral moments it would have to be "2001" and "Blade Runner"

On all other occasions it would be "The Empire Strikes Back" or the original "War of the Worlds"