Driver's seat in base model.
If you could change one thing, I would say add a tilting headrest to the driver's seat.  Since there is no tilt, I have to lean the seat too far back in order to keep my head from hitting it.  I have rectified this by installing an aftermarket 1.5 inch thick seat back cushion.  Now I can set the seat back more comfortably upright without my head hitting the headrest, since I am 1.5 inch further from it.