I have taken a A321 flight about 2 dozen times between SFO-JFK_SFO and always chose the window in the bulkhead seat. It is easy to get out if you have to use the restroom without bothering your seat mate and I always like to get off quickly. Only negative is you have to put your carry on in the locker above and the one at the bulkhead is full of flight gear so you will have to put it one row behind you.