Dr. Strangelove is just hilarious... No Country is a moody meditation on violence. It contains that feeling of helplessness before it. Plus the transitions, the spacing, the silence is trancing... The Big Lebowski took me a second look, but it's kind of take it or leave it... mulholland drive has to be taken on its own terms. it's a surreal masterpiece, haunting, beautiful, strange. that's really all there is to it... one flew, haven't seen that one in a while... so far as 2001, roger ebert's "greatest films" essay on this one is really helpful...
http://rogerebert.suntimes.com/apps/pbcs.dll/article?AID=/19970327/REVIEWS08/401010362/1023