Buddy Rich! And that's all I have to say! But since this is about pool,,,, only because I have heard insane stories about him, I will say Harold Worst!
Buddy Rich is a great drummer, but I'm afraid that there are MANY great drummers. (Billy Cobham, Dennis Chambers, Neil Peart, etc.) It's tough with music because it is very subjective and there are not the same types of measurements of performance.
I've also heard stories of Worst. I've also heard some pretty amazing claims about Don Willis. Luther Lassiter is quoted as saying that if he had one shot to make for his life, live or die on whether the shot is made, he would want Don Willis to shoot the shot for him. It would be tough again, though, to consider him since his accomplishments are largely anecdotal. I think *one* part of being the greatest ever at something is that you need to win the very biggest competition that endeavor has to offer. A great example would be Dan Marino. I, and many others, believe that he was the greatest passer the game has ever known. He certainly has (or had) pretty much every passing record there is. However, his lack of Super Bowl championships are a major factor why he might not be the GOAT.
Still, glad for the contributions...I'm gonna watch some videos of the two guys you named!!