Sorry but have to disagree about the statement that in all likelihood a new joiner would go on the Boeing. The Airbus fleet is still training like crazy - new joiners are needed to replace upgrading F/Os, guys transferring to the Boeing, as well as resignations etc. The training load, if anything, has increased lately. For example, some new joiners are being sent to Cairo to complete their Airbus transition course - using the Egyptair Simulator - because the 2 Airbus Sims we have are insufficient to cope with transitions, recurrencies etc.
As to which fleet one would be sent to - historically, an Airbus rated pilot would probably be sent on to the Boeing and vice-versa!!!!!
Just my 2 fils worth........