most stable place on a boat
In my opinion, having slept in both places, I would have to conclude that sleeping closer to the middle of the boat is more comfortable that the V berth for a couple of reasons. Typically the middle or quarter berths are lower so there is less moment during the boat's roll. Also because you are closer to the center axis in a pitch an yaw, the action is less severe. Think of it as sleeping near the centre of a teeter-totter as opposed on one of the ends. I also like sleeping in the main cabin as it is more 'airy' than the V berth. In the summer, with the mainhatch open and covered with bug netting, it is ideal... and you get to watch the stars as you are lulled to sleep.