I hold 3 Oneworld Emerald memberships.

BA, AA and CX. My QF status has plumetted to oblivion.

I achieved and maintain AA only because of their double miles for elites, VIPO2 upgrade certificates, and generally a good customer service reservation service.

BA was attained only because I can get mileage on transatlantic flights between US and London that would also earn me a bonus.

CX is attained only because of that 24hour guaranteed seat availability in most economy class and Business class fares. Plus the priority upgrades when flights are full are nice.

I use either CX or BA 's card to enter AA's Admirals Club lounges within the USA.

Oh, I also hold 3 Star Alliance Gold statuses.. but that's another story.