Like Mary Poppins
In this post, View from the Foothills lists five perfect songs, meaning not instances of perfect songwriting, but rather instances where performer, recording, and song come together in a combination that will never be equaled. In other words, no cover version will ever be able to surpass the original.
Five I believe qualify:
"Bohemian Rhapsody," Queen - This song is defined by its production, as a dismal attempt a live rendition on American Idol a few weeks ago demonstrated ably.
"Unchained Melody," The Everly Brothers - many have tried, including my beloved U2, and none have come close.
"Sinnerman," Nina Simone - Nina Simone makes every song she sings sound like a definitive version.
"Born to Run," Bruce Springsteen - While a solid piece of songwriting, the piece only transcends in the original arrangement and vocal.
"Every Breath You Take," The Police - That synthy-bass line in the original is critical. P-Diddy proved that the original recording is hard to improve upon.