Don't forget you can only upgrade on CX using Asiamiles... won't be able to with AAdvantage miles... Also, being in HK for a few years, you would probably get a HK based credit card, and pretty much the only points program woud be for Asiamiles or Amex rewards... So if you go for an Asiamies program, you would have miles already, so might as well get the status for it, since it is usually next to impossible to redeem CX tickets in J or F unless you have some sort of status with Marco Polo....