Over the last several years have flown to and from Oz/S E Asia on Qantas, BA, AF, Emirates, Qatar and Singapore.
Earlier this year flew LHR-SIN-PER (A380/B777) and then DPS-SIN-LHR (B777/A380) on SQ and would endorse everything that Businesstraveller and Andy_S have said, except can't comment on upper deck on A380, but would say that Singapore were the best.
Enjoy your travels!
AGP