As a QF lower grade FF member, your chances of an upgrade are slim, as a lot of people who in higher QFF tiers get first dibs at offers from QF.
Also, QFF has got more status tiers, CL (Chairmans Lounge, best looked after by QF), WP (Platinum), P1 (Platinum 1), SG (Gold), PS (Silver), then us NB (Bronze),
I used to be SG for quite a number of years, about 3, but it entails flying a lot, or flying less flights, but in J/F with QF/partners that carry a QF flight number.
VFF only has Beyond (don't know why), WP (Platinum), SG (Gold), PS (Silver), and NR (Red).
QF has got their own planes to the US, and also partners LATAM, AA...
VA has got HA and UA, as they are not flying to the US direct for the forseeable future, they have also got SQ via SIN, which is a good one to go with, even though you have to go via SIN.
For VFF, join FB, (Flybuys) too, they are a partner of VA, and you can earn a bit of tier status by buying your groceries from Coles, 10 per month, and also earn FB points, which are transferable to VFF, which can then be transferred to SQ.
Where as with QF, you can join EDRewards, where you don't earn status with their groceries purchase, but they (QF) have got something called points club, but you have to spend 150,000 on ground activities to earn QFF status, (ouch).
Both are more or less airlines, both have upsides and downsides, but the major downside, is that you play with fire, because even if you book your award with QF, they can palm you off to their low cost partnner, JQ which no one has mentioned.
Ek, read up on "don'tflyjetstar" if you want some scary factors on your flight plannings!
VFF don't have a LCC partner, so they can't palm you off to any other airline.
Granted both can have cancellations, or late departures.
I have my flying with both, am waiting to see if AJ retires, and if things get better at QF, a lot of the cost cutting is down to him, good or bad as it is, some cost cutting was prior to his arrival at JQ/QF.