Definitely stick with AA and its partners. AA to LHR and BA beyond is a good strategy. It remains to be seen whether AA will serve any TW "dormant" routes. The key factor for me would be the fact that you can use 1W lounges and you can check in using preferred lines on 1W carriers. Finally, if anything goes wrong with your itinerary (canceled flights, etc.), you know you've got someone to call or somewhere to go to get decent assistance. I've encountered irregular ops abroad on airlines on which I had no status, and it ain't fun.

And if can upgrade a segment here and there - and earn some bonus miles - that's all the better.