Primitive polygon-based games/primitive 3d based games don’t hold up too well graphically, in general. Although clean titles like Alone in the Dark go against that trend. Donkey Kong Country, to my eyes, does not take the upscaling or the enhanced filters of the Retron 5 very well, probably due to it pre-rendered nature. Here is the intro sequence for the game, the first run with all video and sound enhancements on, the second without. In my opinion the non-enhanced wins for this specific title.
Captured via Retron5 — Extremecap U3 at 720p 60fps 30mbps with 48khz 192kbps Audio —- Youtube
Retron 5 settings include HQ2x filter, Scanlines, maintain aspect ratio, all sound enhancements turned on.