Here is a no brainer to me, my favorite is
https://www.youtube.com/watch?v=5FPzjpCVSAM
Rockface Rumble
Nuts and Bolts is great too
https://www.youtube.com/watch?v=rSIRXvwuNNI
the water theme is great as always, but Aquatic Ambiance from DKC1 is way better
https://www.youtube.com/watch?v=fmCNCLT__oA
PLAYLIST
Donkey Kong Country 1
Donkey Kong Country 2