It is often said that a song is often performed best by original performers early in the song's history. In many cases it is true. But in some cases, a cover gets darn close. Other times it is a total failure.
Take for example this cover of Stairway to Heaven done by Heart for the Kennedy Center Awards which in my eyes, is quite amazing:
It is till not quite Zepplin, but still gives me chills nonetheless.
What would you say is the best cover performance not done by the original? (Videos are helpful and encouraged)