PHL is only a base for the Airbus and the 787. Occasionally 737 trips will run through PHL and get overnights there, and there a few planes that go through during the day, but it’s still not a base. Probably never will be due to PHL being very gate limited and AA is going to want to use it for maximizing capacity with 787s to Europe and the XLR whenever that things is finally on property.

PHX use to be an Airbus only base, but it is now also a base for the 737. I would assume PHX had a lot more 737 flying pre being a base which ultimately aided in the decision for it to become a base, but who knows.

Hope that helps.