Having only this year been downgraded to BA Silver I would go for the AA Plat. Traveling (in Europe and Africa) with Silver has no real benefit as even when on other IAG airlines, Iberia for example, Sliver will not get me in to the BA lounge even if in J class.

As others have said the OW lounge access is the only real benefit when in the US so....If I could I would dump BA simply for the reward flight benefits with AA as I can never spend my miles.....ooops Avios.... on where i want to go