Arthur.
It's the most well rounded mix of comedy, drama, and romance available. The acting is superb, Dudley Moore's timing has never been better. Sir John Geiglund more than earned his place in history with that one... Liza Minelli was likable (I'm not a Liza fan). It was well cut, well paced, and everything ended up coming together without a single flaw.
I mean, the Buildings themselves had such character, props to the production design team.... Granted, they didn't over think it. Put meaning into the production design, put lots of it, but never let it be the point... Sorry, just a gripe with a student film I helped out on...
The movie definitely ages well. It's definitely not going to pass as a modern film, but there's nothing about it that will just have you cringe at how dated the film is....
And the music..... Oh, god, the music....
I don't think there is a more perfect movie. I liked Jaws, I liked Metropolis, I liked Dr. Mabuse, and I really liked "A Shot in the Dark." But I can also find one thing in all my other favorite films. Yes, even Robocop... One thing that absolutely pisses me off. Not in this one. It's perfect.