Left out some kinda big ones there, didn't you? The Shining, Spartacus, Eyes Wide Shut, Barry Lyndon, even A.I., arguably.
I'd say The Shining.
I did add them at first but then I saw how huge the list went.
Also I argue against A.I. I loved the movie though.
I did make a marathon once: watched as many Kubrick films from earliest to latest as I was able to get my hands on. I concluded - Kubrick was a perv.
I voted Space Odyssey. Although it's an old movie its' attention to smallest of details and its' fresh ideas keep it on the bar with many modern sci fi movies. If anything, it's only problem was that it was bit slow at some parts.
Edited by Alyster, 01 December 2013 - 01:45 PM.