A friend of mine (BA Gold) just moved to AMS and is in the same situation.
It obviously depends very much on your corporate travel policy, travel patterns and leisure travel agenda. Generally speaking, considering AMS is well connected to EU and the world (albeit not even close to LHR), I think FlyingBlue + a FlyinBlue AMEX is the way to go as if you stick with OneWorld and BA specifically you'll always have to take the 1hr hop to LHR to go anywhere, which might become bothersome if you do a lot of intra-EU short trips.
If you only do a few (say once a quarter) CW trips, then LHR and BAEC might be an interesting option as flying ex-EU allows you to clock more TPs and achieve status quickly. But then again redemptions will have to go through LHR...