Keep you fingers crossed and hope the EU doesn't squash the AA/BA agreement. US has already approved it. If the deal goes forward, you could fly BA and earn AA miles. In any case even today, your AA status will let you use the preferred check-in lines/ lounge etc if you are platinum or platinum exec., as both airlines are members of the OneWorld Alliance.

In my opinion BA offers the far superior product, but like you pointed out you need more points / flying to get things like upgrades and free trips. In most cases people have found this is simply not worth it and so they frequent AA.