I really liked the Van Leer Rose deal Jack White did with her. It put her back on top of country for a while, Johnny Cash, Waylan Jennings, Glen Campbell, and Loretta could hold their own with them.
Cissy Spacek did her own singing in "Coal Miner's Daughter". Later I saw her and Loretta together singing a duet on TV. If I closed my eyes it was difficult to tell which was which. It was as uncanny as John Belushi and Joe Cocker singing together on SNL.