Everyone's eyes are different. You need to experiment a bit. Back in my R/C soaring days, this was a common topic. You had a 100" wingspan sailplane that would sky out in a thermal to a point where the tabulators disappeared when over head, or when really far up or down wind chasing thermals. Oddly enough, for me, the color I could see easiest in all conditions was blue, and I learned to add some contrast like white. Orange and white is a sort of internationally recognized combination for visibility. For me, yellow was useless! A few hundred feet in the air and the color just diffused into the day light. The ebst advise I can give is to just make it pleasing to you eyes and use some kind of contrasting colors.
Type at you later,
Dan McEntee