I dunno. I was pretty impressed with our own Mousethief when I heard him at JenEllen's Mudcat gathering this summer.Here in Portland, OR, there's Steve Eichorn, who, with his wife Kate Power, owns Artichoke Music. A very fine "unknown" talent.
For pickers who should be better known than they are, I'd nominate Pat Donohue, who plays on Prairie Home Companion, and Nina Gerber, who, among other things, backed up Kate Wolf.
Genie