Not a lot. I think I have 30-something thousand on BA, and probably < 10k on AA. They're both still alive, even though I haven't been on either for a while - I have a BA credit card, all it takes is a small charge now and then.

If the point of the question was to determine whether it is worthwhile continuing with one of those programmes, instead of starting with a new one, I think the amounts are sufficiently low that we can probably consider them throw-away. These are essentially residuals from the 1990s, when I flew far less than today. I have not been on BA much in recent years - although I did make a Finn Air business-class trip to London last year. When I have taken AA in recent years, it was probably too low a fare class to count on BA (the card I would have presented), and I didn't bother to check this out in advance (if I had, I would have used my AA card).

I think I had rejected CX a while back (although my limited experience on their aircraft has been quite good), but my mentality at that time was as a BA FF member. I should luck at it with fresh eyes, as a potential member of their own plan.

It would probably mean stopping at HKG on the way to anywhere, but I almost always connect on all my trips anyway, and if the layover is long, I can even turn that to my advantage (visit people in Hong Kong, make a quick trip into Shenzhen, etc.).