From the look of the replies so far you have well and truly opened up the transatlantic divide. The trouble is that on this side of the pond "Folk" is a tradition traced back at least a thousand years so by the time we've covered that we've used the 100 without really bothering with the last century. Maybe best 100 Folk and best 100 blues would sort out the truffles from the caviare. And anyway, what about Sandy Denny, Dick Gaughan, Nic Jones, Jo Ann Kelly, Maria Barton, The McCalmans, Planxty, oh heck, now you've got ME going...