I am about to book return to HKG in Dec QF128 or QF118 .

I am about to book return to HKG in Dec QF128 or QF118 . I have enough FFs to upgrade to business. Would like opinion on B747 vs A330 thanks.

A3300 in business is the winner for me. 

It'll be the refurbed A330 on that route. Although nothing is certain, Qantas have waited until they have this product to go head to head with Cathay's business product. I'd definitely do it on the return leg being an over nighter.

More seats on 747... so might have better chance of upgrade

I tend to agree with hutch.  The chance of an upgrade on a 747 with 58 J seats versus 28 on the A330.

There are 11 or 12 747s left in the fleet, with 9 being refurbed with Skybed II (if only they had put the business suite in a few years earlier!!) So you have a very good chance of getting a lie flat bed, and the skybed IIs on the 747s are newer, so in better condition than the A380s (many of them are approaching 7-8 years old).  Plus you will get the same soft product on both

Flying Gnome, depending on what date in December, QF127/128 maybe on an A380 which will have 78 business class seats available (64 standard business seats, plus 14 first class seats sold a business class) maximising your chances of a successful upgrade.

Thank you all for the helpful answers. I have booked the Tuesday 747 as I see the A380 is being used on this route over this period. I think more chance of an upgrade on the older bird.