I'd have to go with Pete too, even though there are others I prefer to him. (Although I like him, and am happy to have seen him in concert.) His influence is everywhere, and he made a great many people consider their own regional folk music. People would listen to him, and like it, and say "Gee, didn't gramma and grampa and old uncle Jim used to sing old songs about this area and what the people used to do around here?" So in that respect, I'd have to put him as most influential. Woody Guthrie might fall under this category too.