I don't personally like "The Graduate" or "Midnight Cowboys" to the extent to call them the best ever but I cannot disagree that they were ground breaking films in history. I adore "Butch Cassidy..", "Psycho", the Sergio Leone films, "Lawrence of Arabia" and all else...but here are some more which deserve a mention:
1. In the Heat of the night: There have been a lot of films addressing racism but this one shows Sidney Poitier's stellar Performance.
2. Cool Hand Luke: Paul Newman's arguably best performance ever.
3. The Great Escape: The epic with amazing performances all over with Steve McQueen, Sir Richard Attenborough, Charles Bronson et al. An Amazingly shot movie with some fantastic dialogues