In terms of fighters currently in the UFC by division
-Cejudo (not even close)
-Cejudo (not even close)
-Rodriguez (not a lot of head cases here, but Yair sticks out to me more than anyone else)
-Khabib/Conor tie (Khabib tries to act humble, but the guy's a serious low-key narcissist. Conor is Conor.)
-Covington (Can't tell if it's part of his stage persona, but he's at the top based on how he currently presents himself)
-Adesanya (Nothing to say. Guy's totally full of himself.)
-Jones (When you're the best in the world, it comes with the territory.)
-DC (Can't stand the blow to his ego when he loses. Cries like a little bitch)
-Jedrzejczyk (She's gotten more humble than she used to be, but lack of head cases keeps her at the top.)
-Barber (The only legitimate prospect in her division. Young and definitely smells herself a bit.)
-Nunes (Same story as Jon)
-Nunes (See Above)