Go to a shop and they measure your sit bones on this pad thing that they put on a bench. They tell you which width you need.
The white saddle which came with my SCR4 didnt get hugely dirty, went yellow and if i ever touched anything on my bike in winter that had dirt on it and touched the saddle, it had dirty marks all over it.
Black, i think is better, but only if you have black bar tape aswell.
But then the Avator saddle i have would just need a wipe with a damp cloth to clean it.