I own neither white nor black, but I agree with nymifashion that the white stands out more, so I suppose if you want a brighter bag that's more noticeable then the white is for you. The black, though it is equally gorgeous, fades more into the sea of black bags and is really only noticeable to those who are familiar with the brand.
Though white and black are both "shades" and fairly easy to match with most colors, patterns, and outfits, you might also want to consider which color goes best with the clothes and colors that you tend to wear.
Best of luck!