I'd also rather have CX over SQ. SQ is world-class, but they treat *G as nothing, PPS is deeply flawed (imo) and I'm not entirely convinced with their premium product. I think CX is better in almost every regard except for food in Y and the Kangaroo Route. Losing SQ for CX would allow Oneworld to have a near-monopoly on LHR-SYD flights. (SIN is more convenient than HKG) Regardless, being able to earn miles on CX while flying AC would be a dream come true!

Other airlines I'd like to see in *A would be:

VS: Complements BD's short-haul network well with long-hauls out of LHR. Great style and product, maybe a little too "sexy", especially compared to BA which is anything but.

9W: An Indian carrier joining is inevitable, so it might as well be the best one. I'm sure they could work out a way to split the market with LH and they both offer good products so it would make things only better for customers.

BA has a network any carrier would be jealous of and while they're a symbol of reliability and unity across the old Empire, I think I would rather have VS and BD instead. Unless my travel patterns force me to go to a lot of obscure places or fly LHR-JFK a lot, I'll accept fewer destinations in exchange for the Virgin style.

As for the other Virgin family members (VX and DJ), I'm pretty indifferent. I think VX has the best domestic NA product but I wouldn't give up UA/CO for them! Australia is in a similar situation as Canada, I think DJ joining *A is as likely as WS joining OW.