In the evenings I would suggest they are about even in the respect of food. The Wing's buffet is far more varied, but, being a buffet, some of the hot food tends to be overdone even though it replaced frequently. The SYD FLounge food I had was fresh and perfectly cooked to order; but oviusly not as many choices.
The drink service is about the same.
The Wing has the cabanas, the QF FLounges have the Spa (but not after 5pm).
Some, like mrs serfty find the wing's decor rather stark. I found most promotional 'photos of the SYD FLounge made it seem rather harsh; actually being their I found it a lot 'warmer' and comfortable than I thought.
All in all; I feel it's about equal. In reality, any traveller should be quite pleased to have the use of the Wing or Pier or MEL/SYD Flounges for a few hours in an evening.