I think it has more to do with brightness than color. Anything day-glo (yellow/orange/green) or anything unnatural (pink, light blue) is good. White seems to get dirty and be surprisingly hard to find. Regular orange isn't very good in fall leaves. Red is always surprisingly hard to find. It seems like it would be a good color, but it's usually too dark. Dark blue is terrible, but I have some sparkle blue Comets that always surprise me the way they stand out.
I don't like online ordering that just offers "lighter" or "darker" for color choices. When I ask for lighter I mean I want something that's easy to find. More often than not though I get a pale yellow, or dingy white. Those are light, but they aren't bright.