What color stands out better—-white, yellow, orange, or light green?

I go with a florescent red/orange.

I was never happy with the sight picture of any sights where I tried it.

If I can't have a fiber optic, I want flat, non reflective black.

I use blaze orange nail polish.
(I have daughters)
My personal preference is orange as it stands out in contrast to my eyes the most and helps my far sighted ass focus on the front sight.

I just bought one where the previous owner went with white.

Disappears with my old eyes in bright sunlight. We get a lot of that here.

I also prefer flat black (no paint) but orange would be the choice if I HAD to.

I don’t paint but have experimented with a way to get a more precise aiming point that really does work. Buy a spare front post, then source a nut that shares the same thread pitch. Seat the sight firmly in the nut, then lock it into a drill press chuck. Start it spinning, and shape the tip of the sight against a fine file. Doing it this way gives a surprisingly clean, manufactured look, rather than a lopsided bubba-esce profile.

The angle of the grind is up to the user, as is the decision to work the post down to a point, or just a flat top that is only a fraction of the original width. I like leaving the tiniest flat top on the tip so that I retain the same aiming reference when picking up any other AR. Finish with a light coat of flat black Krylon and install and sight in. Group sizes shrank noticeably for me.

Thanks for all of the suggestions!

I ended up going to Wally World in the cosmetics section and found a small bottle of very bright orange nail polish aptly named "Traffic Cone."

Both ARs now have their nails done.