If you're looking for visibility (I am), I agree with Allan that orange is the best; black is great under flat light/glare conditions, too. I use Congo Hair, a poly yarn that does a good job shedding water, which helps with floatation.
If you want to use wood duck, but don't want to pay the price, substitute mallard dyed wood duck; they'll be very elegant looking flies with either.
Regards,
Scott