Love them both; I would have to give Plant an edge for emotional content (see "Since I've Been Loving You" for an absolutely stunning vocal experience).
Daltrey is in an unusual position in that his best work was essentially that of a cover artist, as he was interpreting demo recordings made by Pete Townshend & submitted to The Who as a whole - his decline is related directly to that of Townshend and The Who - his solo work was never up to Who standards. In his heyday, though, his voice was powerful enough to strip the chrome off a trailer hitch at 30 paces, so there's an edge there.
Love them both; I would have to give Plant an edge for emotional content (see "Since I've Been Loving You" for an absolutely stunning vocal experience).
Daltrey is in an unusual position in that his best work was essentially that of a cover artist, as he was interpreting demo recordings made by Pete Townshend & submitted to The Who as a whole - his decline is related directly to that of Townshend and The Who - his solo work was never up to Who standards. In his heyday, though, his voice was powerful enough to strip the chrome off a trailer hitch at 30 paces, so there's an edge there.
Were I to just consider the work each did with the groups I would give a slight edge to Daltrey, but looking at their entire life work I have to go with Plant.