Don't get me wrong, I liked GWTW and I too have heard it referred to the best movie ever made, and I know many agree. I don't. Call me wacky. I'd have a very very hard time narrowing it down to one movie, BUT, even still, I think the GF is much better than GWTW.
TIS
the godfather part 3 is better than the first godfather and GWTW combined