I'm a *A flyer, but every now and then for reasons beyond my control have to take a OW flight. It happened once this month already, and looks like it will happen again on a long trip in December.

I need to join a programme to stop these miles going to waste, my question is which one is best?

Most of the flights will be ex-LHR (and normally with BA)
Most of the flights will be in discounted economy
There probably won't be very many of them!

So my considerations are:

Must give points for discounted economy
No expiry of points as it'll take me some time to build up anything worthwhile
Awards probably more important than tiers (given infrequency of flights I'll never get anywhere in a year, status wise)

My understanding is:

BA is not good for UK based flyers

AA can't be joined by UK based flyers due to some arrangement with BA

What I've read here and elsewhere leads me towards QF. (I also understand that if I'm quick, QF will credit BPs generated up to 30 days before joining the FFP.)

Any advice you can offer would be much appreciated!