Not really decided yet, but an interesting entry would be a Tacoma Baritone guitar (Thunderhawk BM6c) (what a lame name) that I strung the treble top three in gut (tennis racquet gut, actually-- yeah, they still make gut for tennis racquets) and the acoustical properties of the gut are are pretty good--and zero string winding noise up sliding up the frets. I thought the metal trebles sounded a bit twangish, and the gut filled the bill.
   The guitar fairly cries for alternate tunings, as strung b-B its really too low to sing from.