Thank you. I should mention that no matter what, I will be sitting around airports for a while. If I take the earlier departure at 2:30 on QF/EK I will spend time in MEL and not arrive until 11:50pm. With the nonstop on QF, at 3:55, I'll just have more time to sit around SYD but will arrive in SIN an hour and a half earlier at 10:15. I have no where else to go, disembarking a cruise that morning. I won't risk booking morning flight though as it will take time to get off the ship, get to SYD, and get checked in on an international flight.
Singapore Airlines has a nonstop option at 11:00 but it's a LOT more expensive and I think 11 might be cutting it too close.
Sadly, business class is not an option.
The frequent flyer miles issue is a good one to bring up though. QF is definitely a better option for me, if I can earn AA miles. That's what I'm leaning towards now, after reading all your responses. I wonder what the odds are of the price coming down in the next few months.