Thanks for the question Peter. They've been in short supply lately!
My (very predjudiced) suggestions. Shoot AT FIRST(!!) for the blues folk who had (have) good timing. It keeps you learning good habits. After a bit, try the idiosynchratic (sp) ones who play 5 beats to the bar and 11 bar blues. You can then decide whether you want to copy their mistakes or not.
Josh White: One of the most technically accomplished singers and player. Thought by a lot of people to have been "too" slick. Big Bill Broonzy: A master. When drunk, a lazy master. Blind Boy Fuller: tremendous technique. Dick Justice: He was WHITE(!) and could play Blind Lemon Jefferson note for note. Superb musician. Lonnie Johnson: clean, clear, and totally in control.
Some of the more idiosyncratic (I'll spell it differently this time) players.
Mississippi John Hurt: Simple sounding, HARD to do right! John Lee Hooker: 2 and a half chords and a great voice. Lightnin' Hopkins: Knew how to play in time, but often chose not to.
The greatest technician: Blind Blake. The most feeling: Robert Johnson