Sydney to Singapore in Qantas economy: is the Boeing 747 or Airbus A330 better?

Thanks for the BNE tip, wasn't aware of the refurbed B747 dedicated to that route.

It's normally run by a 744ER, I believe, because the plane that flies BNE-SIN is the one that flies LAX-BNE.

You should still check, though.

 The 747 is too outdated Definately go With the A330 it has better conifguration plus better seats

Not really, the ERs and the GEs have better seats than the A330s; the A330s are only better than the RRs.