There seem to be a lot of folks who are naming their favorites, without regard to versatility. I love Leo Kottke, Norman Blake, Doc Watson, Danny Gatton, Adrian Legg, and some of the others mentioned. But I don't know if versatility is necessarily their strong suit. Again, Martin Simpson and Ry Cooder ar ethe two that come to my mind most readily.

Caveat: I could be giving some of these folks less credit than they deserve, since I can only go by what I've heard of their music, which may not reflect their full range of talents. If anyone wants to champion any of the folks on this list, and point me in the direction of recordings that showcase their versatility, I'd be grateful.