GSP was a goat-level fighter, but he always seemed to fight out of a fear losing, he never had that "I am god" swagger. BJ had it, I thought he could take anybody who was even close to his weight in his prime. It's a major reason why he has his reputation. Fedor would go anywhere with anyone until he got old and it got him tapped/KO'd. If you count delusion as confidence, there are quite a few people who we know would fit too.