For travel around Christmas, I'd be looking at whatever had availability, to be honest. Surely award seats then are going to be scarce.
But assuming there are award seats available on both Qantas and Virgin, it's pretty even. As far as I can tell, Elevate requires slightly fewer miles for that trip (and similarly low taxes). But there could be a better saving overall by using AA during a very good promotion.
If you do end up choosing Elevate, I believe you'll require about half as many miles if you fly SYD-TSV rather than CBR-TSV (presumably both via BNE). AA of course takes a "one price fits all" approach.