Other Perfect Movies

I just love The Thing. I have for decades. I think most of us here feel the same. I quoted Adam Savage in a comment here the other day, who said "The Thing is one of my favorite movies. I have almost no qualifiers for it. It's a perfect movie."

It got me to thinking. What other movies do you consider to be a perfect movie? Personally, No Country for Old Men comes readily to mind for me... but nothing else quite so easily. I'm curious what my fellow lovers of The Thing also hold dear as other perfect movies?