Andy Irvine And Paul Brady . Literally changed my life, when I heard it in Ireland, in 1979. Up to that point, Irish balladry meant something else to me, but this made me check out my Irish musical roots, more carefully. Jethro Tull . Thick As A Brick .
Amazing guitar sounds, and a great long lyric.
May be the ultimate folk ballad. Nic Jones . Penguin Eggs . King Crimson . Tony Levin, the first bass player I learned to identify by name and sound.