I'm a QF FF currently planning a OW RTW itinerary. I will be flying from ORD to FCO via LHR, and am curious for some suggestions as to who to choose between BA and AA. Instinctively I would fly BA, however there is an AA flight which has a better connection. The AA flight is a 772, as opposed to a 744 on BA. Having only flown AA domestically in the US I am unfamiliar with their international economy class product. Any suggestions greatly appreciated.

Thanks in advance.