Qatar and BA have the best route network for MiddleEast/Africa destinations from London, so you'll end up mostly on their planes when flying oneworld and their FFPs would be logical options to switch to.
Full-fare Y travel earns well in all programs. However, there's nuances, and AA is stingier there than both BAEC and QRPC.
BAEC treats Y, B and H fares as full fare on Qatar and itself for points earning purposes. AAdvantage only awards 100% miles for the most expensive Y fare bucket on Qatar, and Y/B on BA. Earning on both drops pretipiously beyond that. So sticking with AA is not the best choice unless you really buy full-fare Y tickets.
QRPC also classifies Y/B/H fares as full fare, and they let K/L/M/V fares ('economy value', the next tier down) earn at much higher rates than you'd get with AAdvantage or BAEC.
Qatar usually offers lower pricing than BA, and chances for op-ups into business class are best with (high) QRPC status. If you (have to) fly QR mostly and buy less-than fully-flexible Y, switch to QRPC to maximize earning and upgrade opportunities, with BAEC a consideration only if you typically fly them on Y/B/H fares.
Qatar does not offer premium economy, and they reserve their own (very nice) lounges in DOH and LHR for premium cabin passengers only. Status passengers in Y are relegated to rather subpar lounges at those two airports. Especially at their hub in DOH, that is really annoying.

BA has premium economy, which earns disproportionately well in AAdvantage. If by "Y+" you mean you can buy into that cabin, fly on BA and stick with AAdvantage (or move to BAEC for taking advantage of POUG/AUP upgrade options).

How close are you to lifetime status on AA? Three years of EXP with 300k+ miles towards milion miler status (if you stick with AAdvantage and fly on high-earning fares) is worth considering, especially if you'd be able to use those SWUs for (personal) trips back to the US.


While Etihad is indeed an AA partner, the FF partnership is limited to only earning redeemable miles (no EQM) on EY flights, and they do not recognize AA status for priority services in the air and on the ground - no lounge access - at all.

BA has various upgrade avenues, which do require FF instruments (avios) or (attractively priced) cash payments. Check the 'AUP' and POUG threads on the BAEC forum. These are especially attractive for upgrades from Premium Economy into business class. From economy, these will only get you into Premium economy, though.

Also note that is possible to upgrade full-fare BA tickets with AA miles. See details here: https://www.aa.com/i18n/aadvantage-p...r-airlines.jsp

Qatar is known for operational upgrades. Chances are fairly high of op-ups into business class happening for high-status QRPC members.
Also, QR offers discounted online upgrades as well. See here for examples ex LHR.

AA, unlike its two large US counterparts, currently does not waive the spend requirements for members based outside the USA. But that should not be a concern when buying <100k of (expensive) full-fare Y fares on partners annually.