I flew from Australia to Europe with Singapore Airlines and they were fine - good price and good service on board. They were also quite helpful when we discovered one piece of our luggage had been damaged and gave us the necessary paperwork for claiming back the cost of repair. I've heard good reports about Emirates but haven't flown with them myself. Qantas have been a bit in the wars lately with various safety issues. I guess it also depends on what you're after in terms of service (economy?), stop overs etc.