If you consistently buy WT+, BAEC is not bad. The main complaints about it come from AA frequent flyers due to the extremely low earning rates on discount Y (AA people tend only to use BA intra-Europe where WT+ is not offered.) Starting at about $1,200 return transatlantic, with upgrades into J for 12,500 miles, and BAEC Silver (OW Sapphire) after 16 segments, WT+ is very good value if you do a lot of longhaul to and through Europe. Silver with BA also gives you Admirals' Club access domestically when flying AA, which may or may not be useful. If you are able to buy Y-UP fares for work AA ones also earn an inordinate number of BA tier points for the cost. In short it can be a very good second program if you can maintain status on your domestic carrier of choice without putting all your TATL travel on their or their partners' metal.