About 8% of American men are color-blind in various degrees--which means having somebody else recommend an optic bead color might not help. This can also apply to a lesser extent with various metal beads.
Have used a bunch of "iron" sights, and while the flat-topped Patridge or other post can work well, it depends on how far you might shoot. Most hunters today consider non-optical sights for close-range shooting, but have killed a number of big game animals at 200-350 yards with various front sights and an aperture rear. (The 350-yard shot was on a Quebec caribou.)
Have used fiber-optic beads, and while they present a very defined aiming point, have also seen a few knocked off their base. This still leaves something to aim with--maybe, if the light's right. But I also don't generally carry another bead in the field.)
In general gold/copper or silver work well, especially if you a fine file to angle the face of the bead (or even a post) at about 45-degees away from your eye. This not only picks up more light, but eliminates the "hot-spotting" that can occur with a round bead, where a reflected tiny point of light can cause the rifle to impact slightly differently, depending on the angle of the sun, etc. Using a fine file even gives the bead a slight glow, due to light reflecting off the tiny striations in the angled face. (Believe I read this in Townsend Whelen's writings years ago, but it was quite a while ago. It works.)
