Originally Posted by
patmcpsu
With all else being equal, would you recommend that I fly BA (AA codeshare) or AA as a PLT?
If you had some Avios there may be a case for booking under BA so you can potentially use them to upgrade to Club World. If you have an Amex card with a few points going this may be one way to achieve it, but proceed cautiously and check further before doing anything. Also if you are PHL_LHR and back on BA metal on a BA 125 ticket issued by BA.com you may get a POUG offer for a cash upgrade (see the Dashboard for more information).
Neither of this impinges on seat selection, whether booked via BA or AA you get free seat selection as Sapphire. It may be easier to do on BA.com but if all else fails a telephone call should resolve. By doing a dummy booking on BA.com for a fully flexible WTP seat you should see what is available or via ExpertFlyer.