use whatever colour the characters hair is normally. I have never seen consistent coloring for the other ref pic.
also, pure white wigs can often look creamy or even blond in the wrong lighting while a bit of silver tone to it keeps it looking in the cool tonal range. you'll have better pic results with even a silver/white blend wig than pure white. I used to use the silver white #60 from newlook wigs for white haired chars just to keep them looking fresh under bad con lighting.