The Wizard of Oz most 'influential' film of all time according to network science. The Wizard of Oz, followed by Star Wars and Psycho, is identified as the most influential film of all time in a new study. Source 8l.
I've always seen old folks talk about the movie Ben Hur starring Charlton Heston as though it was the movie of all movies.
For me, I like movies about survival and sacrifice. Two that stand out for me:
Last of the Mohicans (1992) Daniel Day-Lewis and The Road (2009) Viggo Mortensen.
Of course there is the Matrix Trilogy which is influential for the way it shows how most everything in life is an illusion created to cover the ill-treatment of mankind by the few.