Definitely go on the 787, and go for a window seat.
The seat offers aruond 50% more personal space, is longer wider and a much more comfortable sleep (also a good deal nicer than the older EY seats).
Service is good on both and you won't get status aknowledgement on EY, but the seat is miles ahead of AB. Just as a reference, the AB seat is EY's old seat, 2 generations prior to the 787 business studio.....