Gahhhh...Only one??
I have 3 of my favorites off the top of my head. I CAN'T narrow it down!
So I'm breaking the rules and telling all three:
Four Star Mary: http://www.fourstarmary.com
Awesome rock group, got some cult fame by being the alter-ego Dingoes Ate My Baby on BtVS.
Tony Lucca: http://www.tonylucca.com
My sex god. AMAZING man. My first childhood crush. He sounds even BETTER live.
Howie Day: http://www.howieday.com
SUCH a great performer live. Amazing with his looping equipment. Literally a one man band.