I'd say take QF, get the miles and enjoy the lounge access/status, etc.
However, I've just checked this for you and this may sway you back the other way:
Originally Posted by OW Promo T&Cs
An Eligible Participant is: a member of the British Airways Executive Club with a preferred mailing address in the UK, Ireland, Germany, Canada or Japan and aged 18 or over who has earned or spent BA Miles during the 12 months prior to and including 1 January 2006, and who is not an employee of BA or of a BA Group company. BA reserves the right to verify the eligibility of Eligible Participants.
So
Pyeinthesky Jr. probably won't get the 12K anyway
Phil