No, I'm not qualified to compare their entire musical corpuses. Or to comment on music at all. Let's just look at each one's signature song, from a philosophical perspective.
In "Rocky Mountain High," John Denver wants to go off into the Rockies and "try to touch the sun," "walk in quiet solitude," etc. Now, as an introvert, I find this VERY appealing. And I like Nature. I do. And in fact, I really like the song. But on a closer listen, JD does not like people. He does not want people following him to the Rockies ... "more people, more scars upon the land." So, getting off by himself in the mountains, for John Denver, is SALVATION. "You might say he's born again. You might say he's found the key to every door." Granting that we all need a retreat and some beauty now and then, getting away from people as a permanent lifestyle is pretty dang self absorbed. Of COURSE most of our problems will vanish if we just get away from the dang PEOPLE!
... Meanwhile, in "Man In Black," Johnny Cash is going to tell us why he's always wearin' black, why we never see bright colors on his back. Turns out that he wears black for "the poor and beaten down." On a first listen, I must admit the content of this song simultaneously inspires and annoys me. As a middle-class person who is very susceptible to guilt trips, I question the populist assumption that a class war is raging and everyone is either a victim in it, or an aggressor. And, c'mon, Johnny, did you REALLY decide to wear black at first because you represent all oppressed people? Or was it because you like black and it looks better on stage?
... But having said that, the attitude expressed by "Man In Black" is miles ahead of the one expressed by "Rocky Mountain High." Although I may find Johnny's populism kind of grandiose, it isn't a pose. It's sincere. Johnny really is very concerned about people who are struggling. He grew up poor, he really identified with prisoners. Above all, Johnny's signature song is about OTHER PEOPLE. Actual, other people. This is what gets him going ... the life-and-death struggles of other people. He sings about that with as much passion as John sings about ... himself, alone in nature. What more need we say?
The endless progression of Beast Quest series by Adam Blade
Sasquatch: Legend Meets Science by Jeff Meldrum
Meldrum reviews the evidence for a large hominid living in Northwest North America, from historical sightings and hoaxes, Native American traditional knowledge, footprint casts, and films, all the way to paleontological evidence of Gigantopithecus.