Let me just say that I believe there are two types of movies. We're talking about films which follow the rules. Not other films that won't know a rule if it hit them in the butt.
There are films which are great. They are operating on all cylinders.
Then there are films that you love because you do. They may miss some of the rules, but you still love them, and can watch them over and over again.
So to me, when we hear talk (I've always wanted to use that phrase) of the greatest films of all time, I always want to ask, "which ones? The ones I love and can watch over and over again or the ones which are firing on all cylinders?"