I've recently had the chance to obtain Platinum status with VA, which has given a chance to directly compare the benefits with QF, flying with premium status on both airlines. I do the MEL - SYD route weekly.

I'd appreciate other thoughts of other frequent flyers when choosing between the two.

In summary there is no clear winner, which makes it either a price or rack up your points game on your preferred airline.

QF
- Slightly nicer lounge in MEL
- Premium security lines at all time of the day
- Internet access (most flights) is free
- Lifetime accrual of status points

VA
- Slightly smaller queues when boarding
- Less walking
- Better food in lounge
- Security much quicker when going before 10
- Access to Economy X when booking - not quite premium economy but almost
- No Internet access :-(

Noting both Sydney lounges are often overcrowded, I wouldn't recommend either of them.