A very popular combination is a narrow fiber-optic front, and plain black rear. You do still see white dots, wide fronts, fiber-optic front and rear, plain black, etc.
I don't like anything cluttering the rear but as noted, it can be very personal. Some really good shooters do "odd" things, changing a square rear notch into a pyramid shape, using dots on the front matched with a U-notch, but you shouldn't necessarily base your choice on what any one other person does with their sights.