I use clear and the new CMT lenses on very bright days, Orange really Stands out, also the dark orange but if only had one choice it would be clear lenses.
I have 7 different color lenses with me at all times, all are Rx lenses as i am near sighted, but corrected to 20/10, very good vision and I take Occuvite Vitamins every morning, have eyes like a fighter pilot, as told to me by my eye doctor. I mostly use Clear, CMT, Dark Maroon-Dark Red, depends on the color of targets thrown and also if they have the Black Rim, I prefer solid 100% painted targets, Orange, Green, White.
I agree with those who picked clear. However, clear isn't a color.
I use light yellow and light pink (rose, vermillion, whatever one chooses to call it). I go with yellow on overcast days and under the lights. The light pink is best on bright days and green backgrounds.
I used only the target orange for many years, I could afford only one lens and it worked well for me. Now I use it only for overcast days, preferring bronze for bright sunny days and light purple when its partly cloudy but not overcast.