I would have stayed exclusively with AA, but their removing non-stops between JFK and ZRH and other intl locales was the "clincher"; via my EXP status I should be able to complete a DL PLT challenge...maybe even make DM.
PS: I'm a leisure traveler, so I don't
have to go anywhere, but when I do go I want the least hassles, like connecting in LHR and/or PHL.