Hi all. New here, usually fly United. Found a good deal to Barcelona and am trying to decide between BA and AA flying back

BA: BCN-LHR-IAH, on a 777 for the transatlantic, looks like 3-3-3
AA: BCN-MIA-IAH, on a 777 for the transatlantic portion, 3-4-3

We are a family of 4, 2 adults, a 4 year old and an almost 2 year old in his own seat.

Which would you choose?

Thanks!

(also cross-posted on AA board)