I LOVE DKC!! IMO, the best one id Diddy's Kong-quest, although the first one is definitely a classic.
I enjoyed playing DKC3 (although Kiddy felt quite a lot like Original Donkey).
DK64 was a hard pass for me… I don't know if it was the overall bad quality of 3D rendering or the massive collect-a-thon, but didn't enjoy playing it.
Returns is fine, visually impressing, although I still think it lacks some "soul" that you could find in the originals!