Varig is about to bankrupt. It could be kicked out *A

I haven't followed the events with Varig - only know some folks who have their awards booked on Varig are wondering what will happen to them should Varig bankrupt. It is just a matter of time.

Here is my choices for flying to different parts of the world - AA for South America and Caribbeans.
Europe is OK but not quite convenient since Swissair chose to join *A instead of Oneworld. For the time being SwissAir still AA partner. A friend just has her biz award to Russia booked on AA miles - domestic (Midwest region) AA, Transatlantic BA, changes plane in either Geneva or Zurich I forgot, SwissAir to St.Peter*****urg. Return is from Moscow on SwissAir, changes plane to BA at Geneva I think.
AA now flies to Shanghai. So that is an improvement from before (NRT is AA's only Asia route before).
Sure you can fly CX, but cheap fares on CX do not earn mile. Award seats on CX are hard to come by.
AA does not fly to Australia/New Zealand. Cheap fares on QF only earn 20 or 30% miles - OUCH! Award seats on QF using AA miles are hard to come by, even worse than CX seats.

UA - hands down for Europe awards because of LH. It also has much more choices for going down under because you can fly UA, NZ and AC (via Hawaii, can do a stopover there too). UA also has a lot more routes to Asia than AA who only flies to NRT and PVG. Also SQ is still better than CX in many ways.
However, UA routes to South America has very poor choices.

That is why one needs to cumulate miles on both airlines.