I would call MJH a bluesman, but I would readily concede that he was much more eclectic than say Son House or Lightnin' Hopkins. He was not a bad slide player either. I rate his version of Casey Jones, which absolutely lives from the slide. He did have a more ragtime feel to his playing and there was always that warm, compassionate laugh just behind his music.
I really admire Robert Johnson snd Skip James.Like a previous poster, I love the eerie wail of his voice and his open tuning minor key blues. For the electric players, I always loved that full, warm slide guitar of Elmore James. "Sho Nuff I Do" and "Quarter Past Nine" were favourites years ago when I had the album. Blind Blake was a tremendous guitarist, of course, but I like his world weary voice on "Police Dog Blues" too.