What color is the dirt in your area? I almost never wash a car, and around here beige works the best with silver being 2nd best.
Had a white car get hit in the winter while legally parked under a parking lot light, so never again will I buy white here in the great white north.
For visibility gold, orange, or red are best.
We rented a royal blue Altima years ago while on vacation and got several complements.