Perhaps my most favorite track from Knuckles' Chaotix is the track that plays during the Bonus Stage.
It was also a fun stage to play as well as the special stage, both featuring polygonal graphics, though this was more noticeable in the Special Stage as you where running through a tube where as here you where falling down a hole and the polygons where used to draw the boxes.
As for the music itself, it's a quite upbeat tune that kinda makes you wanna stay in the stage as long as possible to keel listening to it. :P