I can't tell if you're 1K or 1P from your profile, but if you're the former, then I'm not sure you'll be as happy with the switch. You won't have any upgrade instruments to avail yourself of on that route since QF operates the flight. You also will not be able to prebook an extra legroom seat (e.g. exit rows), without forking over cash.

Depending on the rest of your travel patterns, UA may be a better fit for you to MEL. Now, if your travel does take you elsewhere that AA serves, I think the perks of EXP are much better than 1K (F lounge access, upgrades from any fare, very high success rate on upgrades). 1P vs PLT, I'd give the nod to 1P because of the upgrades.