Both flops, in fact, all 30 teams flops. Usually older teams flops better because their years of experience have allowed them to pick up tendancies of certain referees.
I am not sure what is meant by who flops better. It really depends. But if you look at charges drawn, Raja Bell is at the top of the league a few years running, Ginobili on the other hand isn't.
Horry and Oberto are really pretty good floppers, but they play relatively insigificant roles with less minutes. Bell isn't bad, and Nash is pretty good as well.
On the other hand, Parker gets an incredibly few amount of FTs based on how frequently he drives into the lane, and Duncan is shooting career lows in FTAs this year, so that tells you how weak they are at flopping. Shaq flops once in a while more to entertain himself, he doesn't really do it much, Amare Stoudemire doesn't have the mental capacity to understand the benefits of flopping, same could be said for Barbosa. Hill is pretty good at drawing contact, but I don't really see him as much of a flopper. The Suns don't play their bench, so any flopping that is done their is insignificant.