Probably Robert Eggers as well, but he's neck and neck with Ari Aster for me

Excited for Beau is Afraid. Hereditary was a horror masterpiece and Midsommar, though I've only watched it once, has stuck with me unlike any other movie since maybe requiem for a dream.

Favorite might not be the right word, since his films don't like make me feel good or anything. But him and Eggers are basically the only directors I'm guaranteed to watch their films as soon as they come out.