The King Did Not Hang Himself

Question: Shango was the king of the Loa, but who rules the Orisha?

Still Shango!

Possible the most important thing about Shango is the fact that he is The King. Most of his myths revolve around his kingship, either threats to it, laws imposed by it or extending it to conquer other territories, and he absolutely suffers no challenges to his authority. In fact, Shango's identity as a monarch is so strong that that's the entire reason he was also considered king of the Loa, despite the fact that he's of lesser importance in some of the New World religions than he was in the ancient Yoruba one.

There are other figures of authority among the Orisha, of course. Ogun may not be king right now, but he was for a very brief period of time (or, at the very least, challenged Shango fairly evenly for it before giving it up) and has several stories in which the other Orisha ask him to take the throne, perhaps hoping he'd be less insane than Shango when it comes to divine administration. Obatala, whose most common epithet is King of the White Cloth, has never officially been the pantheon's leader but nevertheless wields enormous influence and political power as the oldest among the gods and the one who most often directly works for Olodumare. And Olodumare, of course, is the ultimate authority over the gods, though he doesn't directly rule or interact with them much and leaves questions of law and enforcement to his children to sort out for themselves.

Someone else is only going to get power over this pantheon by prying it from Shango's clenched and dead hands, and even then they'd probably better beware - he has a habit of getting back up after that sort of thing.