For the most part it sounds like AA will be the program for you, for the reasons others have stated. AA also offers a lot more non-BIS earning in the U.S. As long as you're booking AA codeshares on the CX flights or are willing to shell out for Y, B or H. For the upgrades, op-ups may be a far more remote possibility and you can't upgrade with AA miles on CX. But AA's burn rate for straight-out redemptions on CX is supposed to be pretty good.

But... jagmeets raises a good point about the seat guarantee. I've found that to be an extremely valuable benefit. If you often have trouble getting booked on the CX flights you want or have to book more expensive fares when cheaper ones are sold out, this can make a difference.