Tom, the only ones I have used are several different things by Kaufman. I cannot speak for the others, but Kaufman is really good. If you decide to go that way, I would recommend either the 3 Video tapes, "Learning to Flatpick" or if you want CD's the Parking Lot Series is also very good. Either will start you out at a beginner's level. All you will need to know are some basic chords. He'll take it from there.About the others, I would assume that Rick has used materials by others besides Kaufman. I will say this. If it's from Homespun, it's going to be good. Happy Traum is committed to putting out good materials. If you prefer the styles of one of the others, that may be the best way for you to go. As for me, if I could just learn to play "sorta, kinda" like Steve, even at a beginner/intermediate level, MAN....!!!
Randall