Disagree, in the U.S. the original by Johnny Nash reached number 1 on the Billboard chart while the cover version by Cliff only reached #18. While chart position is not the ultimate determination of "better", I also personally have always liked the Nash version, I didn't even know Cliff did a cover until today.
https://en.wikipedia.org/wiki/I_Can_See_Clearly_Now
https://en.wikipedia.org/wiki/Rockers_(1978_film)
https://www.youtube.com/watch?v=5WZY1cEecbI