Looking at availability, I wouldn't be holding much hope of a mileage upgrade on either.

If I wa trying either, I would go for QF2 since the A380 has a lot more business class seats and more premium economy seats than the B787 - plus potential that someone might decide to try wasting miles to upgrade to 1st

With availability for sale being zero in 1st on !F2 and zero on both flights in buisiness and premium economy, if you are booking an economy ticket, I would be expecting to travel in economy