It's difficult to create a best selling list like that, because sceneries have been released in different times so, for example, Zurich has 3 years of sales behind it, while KDFW is only 4 months old.
In any case, JFK is the best selling one, but Zurich and KORD are right up there, and KDFW, KLAS and Geneva are also doing well. But there's not really much difference, they are all doing fine, even KFLL and PHNL are ok, and we are quite sure PHNL has a long life ahead, once we complete the Hawaii airports series.
We never had many surprises: sceneries are selling exactly like we were expecting to, which means sales are basically related to how big and how internationally connected an airport is...the only one that has probably exceeded our expectations is Geneva, we never thought a single runway airport, which is not even the most important in its (small) country, could fare as well as the big US hubs.