Ds lite nintendo

What color of Nintendo ds lite makes the screen look the clearest?
My dad has bad eyes and therefor I'm trying to find the best color. I think the different colors of Nintendo DS have a certain impact on the screen. Correct me if I'm wrong, but I think a black NDS gives the clearest view. I would like to hear your experiences if you had the opportunity to compare different colors.
Thanks guys!

the darker colors only contrast with the screen more than lighter colors making the screen seem brighter. other wise it doesn't matter.