Reminder that AA status requires 4 flights on AA per year to renew. Also while AA may have the easiest qualification requirements, I would tend to question the value of having status on an airline that one never (or rarely) flies with. As an AA Emerald member, I'm sure that one would expect nothing more than perfunctory service and published benefits on both CX and BA.

I don't have a huge amount of experience on BA, but I know that when it comes to unpublished benefits, CX values their own Gold (Sapphire) members much more highly than other carrier's Emerald members.