If you only really fly on the most common routes (e.g. MEL-SYD...etc.) then I'd say VA is really good, but stray away from them and VA just doesn't have the same network that QF does.
This is also only for domestic, for international, QF is far better. VA basically have no real international presence. You could fly SQ, DL or
Etihad, but you'd have to look into whether VFF is the best program for you to credit status and points into.
Biggest advantage with Qantas is probably OneWorld. If you're QFF Gold, you'll have access to all the benefits when travelling with partners. I find Qantas lounges better and less crowded (probably because they have the Club and Biz lounges separating out Gold and Plats).
Jetstar is also a huge asset to Qantas. They fly some popular short-haul international routes. Interestingly, even their economy sale fares credit as a regular economy (with the right bundle), and same with their J. Having flown in J with Jetstar, the seats are comparable to Qantas PE, but cheaper, and with higher status earn rate.
Biggest advantage with Virgin is that it's much easier to climb the status tree. Status pooling is genuinely useful if you travel a lot with your family.
Also, FWIW, I also find better award availability on QF, but others might disagree.
