Hard to beat flat black if the light is good. I like to take a piece of masking take, set it on fire and use the soot to black out the sights. Not very durable but an excellent flat black finish. I have trouble with red or painted sights, if I can't see black then a red dot is what my old eyes needs.

A true sportsman counts his achievements in proportion to the effort involved and fairness of the sport. - S. Pope