FWIW, I use AAdvantage becauser of the extra mileage bonuses for Platinum card holders. I have a BA card, but it has gone back to blue. When my company switched from VS to AA for transatlantic, it made sense to get an AA card and "ditch" the BA one since I can't get points credited to my BA card for transatlantic flights on AA. I still get points for BA European routes.

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Chris Elvin