I agree with the sentiments above. In economy the two airlines are similar. I would say the one distinct difference is the IFE which is far better on Emirates.
I would argue that in business Emirates is the better option because this route is serviced by an A380.
I definitely agree that EK's business class is much better than Qantas's but adding 35% to journey time whilst having to spend 90 minutes in domestic business class of Qantaas would not offset the better Emirates product for me - there would have to be a good cost saving