Split (mild spoiler)
Proves that he's a better director than pretty much anyone making superhero movies right now. He's already made the definitive superhero origin story with Unbreakable, now he's made the definitive supervillain origin story with Split. He's taking this genre more seriously than any other director and taking it to a place, cinematically speaking, that few are willing to go.
He's just completed the second chapter of probably the most unique superhero drama of the last twenty years, now he just needs to bring it all together in the third.