Inspired by one of Alfs threads where we discussed Nirvana's cover of The Man who sold the World being better than David Bowies original (when you actually type The man who sold the World it even brings up Nirvana's version first so they clearly agree
)
The Man who sold the world
Spoiler:
Original - David Bowie
Cover - Nirvana
My next suggestion is Killing me Softly, imo The Fugees cover is the best version of this song
Original - Roberta Flack
Cover - The Fugees