Well, I certainly prefer to buy American, if for no other reasons than pragmatic things like shipping costs, worrying about exchange rates, etc. If multiple sources exist for a ship, I'll buy Tom's- my favorite, or else GMM.
However, these are all small concerns, with limited funds for investment for product development, so I do not feel upset when only one source offers a PE set for a specific ship. In that case I buy from whoever produces it. Ideally, I would like to see it from Tom's or GMM, but I know it is impractical to assume they will always invest in the development for the set I need.