That's a tough one, I'm not sure I could pick just one. I love much of Woody Allen's 70s and 80s work for how funny it is, but he has been much patchier since the mid-90s. The Coen brothers have proven equally good with comedy and dark drama. And when it comes to world cinema, there's a Japanese director called Hirokazu Kore-eda whose work is beautiful in a low key sort of way. He is especially good at working with child actors.