There are so many of them, that it is hard to decide... but I find myself always going back to the same old four..... Sonny Boy Williamsion II, Big Walter Horton, Sonny Terry and Junior Wells...
It is not only the unique sound they produce with their harps, but also their songs and how everything sort of blends together into a musical meal for the soul (if that makes any sense) .... I don't know, I just keep going back to them.....
Just take a listen to this.... (closing your eyes makes the experience even better)