Originally Posted by
fumje
The seat and service will be basically the same.
However, I would slightly prefer the 787 because of the higher cabin pressure. The 757 is blocked for about 10 extra minutes flight time, if that is significant to you.
Agree with both - I would also prefer an 11pm departure for a slightly later flight. However, I would see if there's any obvious reason for the change first.
Note that if you care a lot about aisle access (you probably don't traveling with a companion on a short red-eye), only the 787s have that from the center block of 2-2-2.