On the 787-8, 7E is easily the best seat. It is in the second section of CW, which is much smaller than the front section and much quieter. The middle seat in the centre block is wider than all other seats in the cabin, and in row 7 you have direct aisle access with nobody needing to climb over you either.

As far as the 787-9 is concerned, 7E is in the front section, which is the smaller on the 787-9, but is near the galley/toilets so it may be noisy. 13E is the middle seat in the last row of the second section, but you may end up with a baby on the other side of the bulkhead ...