If you have elite status on another airline, you could get a status match on CX. Being based out of HKG, it would be better to have status with a home airline - which in this case is CX. They treat their elites very well (i.e. ocassional greetings to thank you for your loyalty) and their rewards programme (Asia Miles) is more useful locally (i.e. many credit cards in Hong Kong that allow Asia Miles point exchange, miles for shopping at Hong Kong supermarkets, restaurants etc.) than AAdvantage.

Note that Asia Miles should not be confused with The Marco Polo Club.