OP is you are in an AA hub, BA miles could be useful. Its best to use BA miles on partners that do not charges YQ even if you get a little less of savings, just to hurt BA. When you use BA miles on a partner airline, BA has to pay the partner, so this hurts them financially. If BA had some sense, they would not charge YQ on their flights. Then pax would redeem on BA flights for seats that would have gone empty otherwise and BA would not be paying anyone.

Only if pax vote with their wallet, will they learn to adapt to Rome. Thankfully we have competition and if pax like us do not do the above, then the competition will only follow BA instead of the reverse.