These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Even Trent Reznor acknowledges that Cash's version was like "I just lost my girlfriend, because that song isn't mine anymore..." after hearing it for the first time.
Johnny's cover of Sheryl Crow's Redemption Day seems to be the more popular version.
"I Hung My Head" was originally Sting, but few people have even heard of the original.
Dork Age: 1971-1994, the period between the end of The Johnny Cash Show and American Recordings. Cash did release some grade A material during this period, but between various religious pursuits on one hand, and occasional relapses into substance abuse on the other, he wasn't always focused on music and the quality of his recordings became more erratic.