To narrow it down to a period I'd say those releases from 1969 through 1978 (Sunday Concert to Endless Wire, I think) But I've said it here before if he said he was going to read a telephone book on stage I'd buy two tickets and sit through the whole thing. I enjoy every track he's laid down for some reason or other. But I also believe it has a lot to do with when you first heard him, the circumstances when the inprinting on your brain took place. You scientists out there can fill in those details, LOL.
Bill