I think any seat in the F cabin is fine. Have sat a couple of times in F seat, and once in K.

Gallery is behind the cabin, and lavs are out the front, so the traffic is split. The F/K aisle is shared, but after you angle your seat, you don't really notice people walking up/down the aisle (except perhaps in the F seats if you don't put up the privacy screen (you can see people talking up/down the A aisle)