It'd be really nice if AA had some special lounge agreements with their OW metal neutral JV partners for AC members. For me, when I was in LHR, I did not have AA Plat status at the time, so I had to choose an AA metal flight leaving LHR which would at least allow me to access the Admirals Club as a member.

I would've rather preferred flying BA as an AA Codeshare because the BA flight I was looking at had a better schedule, but since there was no club in T5 to use, I ended up sticking with AA.