BA/QF share the lounges in SIN. The first lounge is really nice and showers are awsome.

CX lounges in HKG have a well deserved reputation and are not to be missed. I like the Wing better but it really depends on where your gate is as to which lounge you need to go to.

BA/QF seems to have the better lounges in MEL (international terminal) and the QF domestic lounges at SYD & MEL are well stocked and very large.

Can't help you out on any of your other stops