When it come to cups in bras, as a general rule (though not going crazy) the more seams you have the better support and fit the cup with be. The most popular of the larger cup, is a three-piece-cup. With two-pieces making up the lower cup and a seam running across the cup for the top cup. The more curve you have on these seams, the more volume will be projected.
The following brands use the three-piece-cup.