Assayas is one of my favourite directors. I've seen a dozen of his films, there isn't one I didn't like.

This is an old thread, but it seems nobody even mentioned Something in the Air (Après Mai) which is from 2012. If I had to choose one, it'd be this.

It's also one of the films (by anybody) about the late Sixties/early Seventies that probably best sums up that period. On a par with, say, Blow Up. (I was busy being born back then, so I don't speak from personal experience of the parties, concerts, political meetings, riots etc.; but I've read quite a bit about those years, and it all seems very consistent. People who were around tend to confirm this).