Long Haul Airlines: What are they like?

At the moment my dad and I are looking for flights to Sydney. We have relatives there and we may be looking to go in February next year. When searching for flights, several airlines have come up, most of them within £50 of each other. Qantas is the cheapest, followed by BA. Another flight that looks intersting is Austrian Airlines to Vienna, then ‘another carrier’ 777 to Sydney. Does anyone know who this carrier might be? What are your opinions on BA and Qantas? Cathay Pacific also come up, as one of the more expensive ones, but from what I guess they are one of the best around. Considering we don’t really have money to ‘throw-around’, who would you take?