Cool thread! I don't know that it is possible to pick a top 10 ever in movies. Each era has its greats.
Here is a list of movies that have stood out to me:
Gone with the Wind - to me the grand daddy of movies ahead of their time
Dr. Zhivago
Das Boot
AI - Best SciFi movie I have seen
Lord of the Rings
Sophies Choice
Modern Times - gotta include Chaplin in the list somewhere
African Queen
Long Day's Jouney Into Night - Hepburn was amazing in this movie
Days of Wine and Roses - One of Jack Lemon's best performances
Kiss of the Spicer Woman