I moved to London a few years ago and endorse sticking with QFF unless you know you'll do a lot of BA C or F travel.

However, bear in mind that unless you fly QF/JQ 4x a membership year, you WONT gain or maintain status with QFF.

I fly BA in all classes a few times a year (not enough to really make it worthwhile to join BAEC), but as I haven't flown QF in a couple of years I don't get status. Still, I'd rather accumulate points on QFF so that when I do fly QF (only takes an Aussie trip and a few domestic flights at the least), it bumps me up in status easily.