Based on your input, I am leaning towards taking AA777 both ways: PHX-LHR and LHR-PHX. I agree that in both directions departure time is less than optimal. However, at least I can pick a good seat on AA when making my reservation, without paying additional fee. ( I have no status with Oneworld)
I flew BA747 many times in the recent past and never liked the seats, except for a couple of them upstairs. Also the lack of storage around some of the aisle seats really bugs me.
Maybe I should give AA777 a try this summer. Or I might just try them both, AA on PHX-LHR and BA back.
Thanks for your input!