A lot of people are picking people who seem to have what I would call "affectation" in their singing, IMO. They might be outstanding singers, but their style often has more importance than the song. Oh well, different opinions...

Female: Maddy Prior, June Tabor, Jeannie Robertson Male: Cliff Haslam is the only one I can think of at the moment. He's only done one recording (a long time ago) that Folk Legacy sells, but he's absolutely incredible.