Wirelessly posted (Mozilla/5.0 (BlackBerry; U; BlackBerry 9780; en-US) AppleWebKit/534.8+ (KHTML, like Gecko) Version/6.0.0.448 Mobile Safari/534.8+)

I think the biggest benefit is that oneworld partners actually see each other as "partners" and this is reflected in their treatment of passengers.

*A members on the other hand have all sorts of complicated restrictions on who can use which lounge and when, who can access this benefit or that and so on. UA E+ and the way LH lounge dragons disdain non-LH flyers are but two examples.