Originally Posted by Stripe

I'd probably pick the LHR connection. A more interesting place to connect IMO, and I would expect LHR-ORD to be less prone to delay than PHL-ORD. Also, do these all have AA flight numbers? If the LHR option has BA numbers check the EQD earnings carefully, if you're trying to maximize credit. EQM earnings will be very similar.

Note that both flights via LHR will be in/out of T5, so no worries about the T5-T3 bus. But it also means you will not have access to the CX lounge. Your PPro status will get you access to the BA Club lounges, which can be quite crowded.

What kind of plane is LHR-ORD? If a 747, the PE section is positioned so you would be one of the first off.