Re: my inclusion of Jules et Jim, I realize I forgot to screen that one out from my Top 5 favorite films. (ie. Citizen Kane is not on that list, but would easily qualify for my list of the 5 BEST Movies Ever, if not my five favorite (although it would easily slip somewhere in slots 6-10 on my list of favorites). So while Jules et Jim is a great movie, I can admit it is probably not one of the 5 BEST movies ever made. So to amend my list:
Casablanca, Citizen Kane, Lawrence of Arabia, Manchurian Candidate, and The Godfather (treating I & II as one whole).
The Godfather - and I don't think anyone else has mentioned it yet, believe it or not. As for L'Avventura, and a few other non-American films that have been mentioned on this thread, I think they are great movies, but, in many ways, too caught up in their own stylistic conceits to be The Best Ever. For instance, the idea of staging scenes in real-time in L'Avventura is a bold idea, much like the concept of the jump-cut that Godard and the Nouvelle Vague gave us. So I would call films like L'Avventura of A Bout Souffle IMPORTANT because of the way they, as representatives of a striking movement like Italian Neo-Realism or The French New Wave, affected and continue to affect filmmaking across the world. But I just tend to feel that with those films, if you get past the fact that the stylistic choices are different, revolutionary even, and assess those films purely on the basis of their form's functionality... then those movies don't QUITE crack my personal Top 5 list.
However, one non-American film that very nearly made my Top 5 Best Movies Ever Made list was Pather Panchali, the first film in Satyajit Ray's "Apu Trilogy." It's terrific and moving and I recommend that anyone interested in film check it out. Oh yeah, Bergman's The Seventh Seal almost made my list, but I've only seen it once, and as a result, haven't really been able to digest it completely and come to fully appreciate it yet. And Bicycle Thief, too. Almost made it.