Best, in my book, is a singer who has expressive control of their entire vocal range, but lets the song take precedence over the singers chops. To my ears Cindy Mangusen does this best, and Deb Cowan is right up there.

Male voices, I'd listen to Gordon Bok sing the shipping report (whoops, don't tell Les Barker that) with the warmth his voice has. Though he's primarily known as a opera star, Ben Luxon (when singing with the late Bill Crofut) sang some damnfine folk, bringing that powerhouse voice to bear. His version of "Johnny I Hardly Knew Ye" had hairs standing up straight from the most complete set of gooseflesh ever.

So those are the best I've heard live ('taint fair to make judgments from recordings), for the range of songs *I* listen to.

Joanne in Siberia on the Heights