And here's a second round of possibilities in no particular order of importance:

Mr Tambourine Man - Dylan
There But For Fortune - Ochs
We Shall Overcome - ?
Bird On A Wire - Cohen
Me And Bobbie McGee - Kristofferson (recorded first by Lightfoot?)
Until It's Time For You To Go - Buffy Sainte-Marie
Summer Wages - Tyson
Song For A Winter's Night - Lightfoot
Hard Rain's A-Gonna Fall - Dylan
Pack Up Your Sorrows - Richard Farina (and Mimi Baez/Farina)

As to whose recording of these various songs you like best...well, that all depends on your taste, right? Joan Baez did sterling recordings of many of 'em, for instance....but only Buffy Sainte-Marie did "Until It's Time For You To Go" convincingly, and she's the one who wrote it and it came directly from her own life experience, so that figures. Elvis and many others recorded it too, but their versions were seldom convincing at all...usually verging on pure schlock. When Buffy does it, it's real and it's beautiful.