Danny was incredible. Used to see him a lot back in the day. Lots of times in little hole-in-the-wall places where there were maybe 25 people in the audience. Those were the best shows. He was just playing to play and doing whatever he felt like. Listening to him just warming up and screwing around sometimes you'd be thinking "Holy shit, what did I just hear?"
The greatest is always a tough call given how many other great players and different styles there are but he was right up there.
Wayback machine:
http://www.youtube.com/watch?v=A50Vi2VQgLA