In my opinion, white is the best color whether for feathers or fur tracers. I'll give my reason why.
Florescent green, orange, red, yellow, hot pink; these colors look great in the daytime. In the early morning when it's still quite dark, but becoming light enough to make out a deer and shoot an arrow, all the colors I mentioned, you can't see them upon arrow release. Ditto for the fading light of dusk before darkness falls. But, if one uses white colored feathers or fur tracers, you can see the white color under the low lighting conditions I've just mentioned.
This is why I fletch my arrows with 3, 5" white colored feathers. This has allowed me to take the shot and actually see the white colored feathered arrow in flight under these lighting conditions telling me if I've missed or my arrow has impacted on the deer's body, preferably the area where the lungs are located.