QP membership gets you into BA lounges when flying BA anywhere in the world and into AA lounges when flying AA; so it isn't just for QF and is pretty useful in Europe (esp. as BA does not sell lounge access separately, they bundle it into the ticket price).

You'll earn between 10K and 20K miles on QFF (depending on the exact fare classes), which is enough for a short free flight in Europe (prob. 600 miles, something like SNN-AMS or SNN-MAN). So not much benefit, but not necessarily orphaned miles. You can find out the earn/burn rate from the QF web site, see for example http://www.qantas.com.au/fflyer/dyn/...s/pointsTables

I don't think any of the other FF plans would be substantially better for you (and some are worse). Crediting to AAdvantage would not earn you more unless you did more travel that can be credited to AA (AAdvantage earns better but doesn't have the low-end awards that QFF has, so you need more miles but get a better award flight).