For domestic flights, I value Velocity points at around 1.4 cents per point, while I value Qantas FF points at around 1 cent per point, based purely on comparing points spent on an economy flight versus paying for that flight with cash.
For international flights, since I am uninterested in upgrades, I haven't bothered comparing as Qantas's taxes and charges have tripled from the last time I used FF points to fly to Europe and back in 2009 - it just doesn't now seem worthwhile to me. Though the OneWorld round the world trip with FF points may still be attractive.
At the moment, the best card to get if you do a lot of shopping at Coles, Worthworths or IGA supermarkets is the Amex Platinum Edge card which earns 3 points per dollar at those supermarkets. And that card comes with a free annual return plane trip if you connect it to the Virgin Ascent program, to which you transfer your Amex Member Rewards points to become Velocity points.
So I currently earn Velocity points on my Amex card and earn Qantas FF points on a cheap Visa card which I use where either Amex isn't accepted, or for where I'd have to pay a surcharge for using the Amex card. Though when travelling overseas I don't use either of those cards as they are too expensive over there.
Regards,
Renato