Top 5 for me (excluding Star Wars) would be -
Horrifically bleak, yet utterly wonderful at the same time. A film that really pushes the idea of society free of rules and regime, and the cinematography in 'The Zone' is just beautiful.
APOCALYPSE NOW (1979)
There's not much to say about this that hasn't been said before, but it's one of the only films I've ever seen that actually depresses me. After watching it, I feel very funny for about 6 hours and I don't know why.
Although arguably a horror (and I think I even listed it as one!), this film introduced to me to surrealism in film, and the beauty of "modern" day stark cinematography. I'd only ever seen Twin Peaks up to this point, so this was the first David Lynch 'film' that I'd actually seen. As a 13 year old I was completely mesmerised by this film, and I still the think that the Lady In The Radiator sequence is one of the greatest scenes ever put on film. Remember, in Heaven, everything is fine.
VENGEANCE IS MINE (1979)
A fascinating allegorical story of a true-life serial killer as metaphor for all the problems of post-war Japan, this is just a stunning film. Ken Ogata plays the most likeable, yet utterly repulsive killer ever put on film, almost a 70's Patrick Bateman, the 2 1/2 hr running time just flies by. Whilst classifiable as a horror film, this is so much more at the same time.
THE CONVERSATION (1974)
What a film! Gene Hackman has never been better than his performance as the lonely, paranoid Harry Caul, and it's never a bad thing to get John Cazale on screen as well. An early appearance by Harrison Ford as a very smarmy man is great too. Without spoling it, the final sequence in the apartment is both breathtaking and devastating in its conclusion. Almost perfect.