Since WHEN AA All Partner awards to Asia require you to route through Europe?!

AA All Partner award specifically requires one to go TPAC for Asia. Yes, if going to Asia via Europe there are 2 awards - NA to Europe and Europe to Asia. But that is not what the OP asks.

The poster of this thread wants to know which program has the least mileage cost to Asia. He does not say he wants to go Asia via Europe.

I dont see any program forces to route though Europe to Asia. In fact, Aeroplan and may be CO in the past, allow you to route through Europe to Asia without additional mileage cost.

It does not matter which program costs less, the importance is which program can find award seats easier. So far CX on AA miles or BA miles seem to be the easiest to find award seats especially getting closer to departure, in F - because CX is a smarter airline which rather gets some money from its partners in the "sale" of award seats rather than letting the F cabin flies empty. Airline seats and hotel rooms are the most perishable commodities when you come to think about it. The smarter ones would hold out their award seats till much closer to departure then release them if it is obvious there would be no revenue sale.