There are many reasons that I think he is one of the better players at the game. First, the results he has had goes beyond the WSOP. His bracelets are pretty impressive, especially as they include the Main Event. His amount of final tables is also pretty impressive. Then there is the fact that he has an impressive run with the World Poker Tour. He has won at the National Heads Up Championship. He has won at an EPT event. He knows multiple styles of poker in a way that is a threat whenever he sits down.
Now, he is the Brat, there is no mistaking that. At the same time, he is actually a really nice guy off the felt and can be such while playing. He may have changed, but I have had a conversation with him in the 90s and enjoyed it. It was just a bunch of folks eating somewhere before a tournament and someone who knew him called him over. He has become an ambassador to our beloved game and people love him.
So, while I personally would never say he is better than Doyle Brunson, I would say he is better than a long list of folks who are nowhere near the personality he is. There are even people who want to get him going off on them, just because he is legendary in that.