Just remember, it is not just a color, but a light. With color when you mix all 3 base color you got BLACK, with light, when you mix 3 base color you got White!
From my limited experience, the absolutely most visible color to a non color blind human is
PINK nock on red LED
follow by Red Nock on Red LED
Just for discussion
This is the list of visibility visible light/led light for normal vision from brightest to lowest on a NULL background (background that do not have any visibility, i.e. matt grey with same light reflection index as the light source), Red, Orange, Yellow, blue, green, and white
For efficiency of current LED technology stage,
The following is what I have found, Red, Green, Orange, Blue, Yellow, and White with (blue, green and white LED being the least efficient)
i.e. current LED technology is leaps and bounds compare to what is just 2 years ago. By next year, you can assure that the Firenock Red will stay lit for no less than 7 - 10 days at room temperature, with the same battery until the battery totally dies out compare to the current 24 hours. No Joke. It is even more amazing when the temperature drops, I have 4 LED in red had stay in the freezer at -3F for the last 12 days already and it is still lit! I shall see how long it lasted......
Blue is coming a long way, so is green.
One need to think of a color of light, not just a color. With light you look for enhancement, not contrast like color for differentiation. So a green light will show better on a green non lit background. So it would only make sense to use green on turkey, but then we added the reflective light from the sun to the equation, the red again wins in MOST cases, unless it is just before the sun is having effective on the reflective part! This can get complicated real fast. All in all, if one is not color blind, red is the best and a hint of red would be better than full red, thus pink on red is brighter as it allow more red light (620–750 nm) to pass.
For your information, for most double color blind, surprisingly beside blue, I discover that green nock on yellow light, which transmitter a more of a cyan (476-495nm) color is what seems to work better as they are the final color combination nock most color blind customer purchase after they looked at the light box said they see the best!