Ra over the others for me by a mile when it comes to Jazz. Though I also worship at the temple of Pharaoh Sanders...

Folk? I really don't know. I'm tempted to say Shirley Collins and Peter Bellamy for the revivalists. All the best traddies are Scottish: Lizzie Higgins, Jeannie Robertson, Stanley Robertson, Willie Scott, Davy Stewart.

... or whoever turns up at your local singaround.