If I'm fletching my own, I go all blue, and use the nub on my knock to identify correct knocking position.
Blue is the rarest naturally-occurring color in the woods. That's why (down here, at least) surveyors use it so often. A smidge of blue in the leaf litter stands out absurdly well. Red, yellow, white, green, orange, and black all occur with regularity, and make finding lost arrows a drag.
All that being said, I hate fletching, and usually go with whatever's on the clearanced box of arrows I end up buying.