:-)
Elton John or Bernie Taupin?
Mick or Keef?
...and a bit more in earnest (I offer no opinion)...
June Carter or Johnny Cash?
Gillian Welch or Dave Rawlings?
Emmylou Harris or Gram Parsons?
Emmylou Harris or Rodney Crowell?
John Paul Jones or Jimmy Page
Michael Nesmith or the others
BTW - good pairings for discussion from @bdp24