I've found as a general rule that, if you're trying to find out who did the original, and CCR is one of the contenders, you can rule them out...(that's not a bad thing, but I've just found it tends to be the general rule

).
I know a lot of people won't know them, but the Doug Anthony Allstar's did what I believe to be the best cover of it...heartbreaking, the way i think the song was meant to be...
Elvis Costello also did a slower version of it which I think it closer to what the song
should sound like (obviously, purely my own opinion) compared to Creedance or Marvin Gaye, but the DAAS version will always be the definitive one for me...