Honorable mentions to all sorts of legendary nats like Virginia Bell, Penny Ellington, Starr Murphy, Devon Daniels, Chloe Vevrier, Autumn Jade, Diane Poppos, Cherry Brady, Merilyn/Anya, Yoko Matsugane (yes, they can hang, even in a bikini), LDM, etc. etc.
But my fave in this category has to be Nicole Peters. 'Tis true--her breast tissue appears to be very soft and her profile may not be as impressive as some others on this list (which is perhaps why she is typically seen posed with one arm cradling her breasts). But God d*mn, when she bends over, she puts them all to shame.