200. Shichinin no Samurai [Seven Samurai] (1954)
This is the film everyone needs to watch no matter what your opinion on it ends up being because it is so influential. It's strange that I've never seen it before. So much has been written about this film that the only thing I have to say is that it really is one of the greatest films ever made.
I watched this film on the Criterion blu-ray about two months ago but I've only just finished with all the special features. This blu-ray is fantastic. Picture and audio quality are as good as you're going to get for your home. The extra features include two commentaries, four hours of documentaries and a booklet with essays on the film. They are superb. Most film commentaries and extras I would only listen to and watch once but these extras are so good that the next time I watch this film I'll reverse the order and go through the extras first. If you watch films at home, Criterion blu-ray is the best way.
"The State is the altar of political freedom and, like the religious altar, it is maintained for the purpose of human sacrifice." - Emma Goldman