I've tried Red/Green/Orange so far.
By far best color for visibility at night is Orange. The blades almost glow in orange and the lights are bright in Orange. Makes orientation very easy. If you have a Red one get the orange canopy, blades, and light pipes. Try it out. The difference is very pronounced.
The Red sort of mutes the light and at night its not as bright. Also the Red blades are more opaqe and don't have the "glowing" effect.
The Green is better than Red at night but not as good as orange. The lights shine through brightly in green but the blades still don't glow as well as they seem to in orange.
During the day I think it makes less of a difference, but my order is still the same in terms of visibility. Orange, Green, then Red.
I have no experience with blue. Anybody try that one have a comment?