Some of these are great personal favorites--which is not necessarily the same as films I consider the greatest. They're not guilty pleasures--they do what they do perfectly, and I like movies that do what they do. From your list: The Great Escape, The Magnificent Seven, the whole Thin Man Series, anything by Howard Hawks.

My own birth year (1950) eliminates a lot of films that aren't from before I was born (Touch of Evil, I Vitelloni, The Searchers, Chinatown, Titticut Follies, etc.), but there is a wealth of great (and enjoyable) films from 1949 backwards, including: Bringing Up Baby (and anything by Howard Hawks), The Miracle of Morgan's Creek, Open City, Double Indemnity, Shadow of a Doubt, Land without Bread, and most of all: Rules of the Game--in my opinion there will never be a greater film.