From a performance perspective, rear cell 100% is the way to go. I’ve had my hands inside a LOT of trucks with every setup you can think of, and without a doubt the rear cells work better every time. Also, every single truck I’ve worked on with a big rear trunk and mid cell was carrying no more than a tool pouch, battery, floor jack, and sailboat fuel, meaning they are dead empty. Also, mid cells are limited on fuel size and shape due to upper link clearance and shock clearance. Everyone has grand plans of loading their big storage trunks up with spare parts and tools and smuckers sandwiches and water bottle and whatever else but only on the occasional long trip is there ever anything back there. Meanwhile you’ll need a full fuel tank for damn near every trip so may as well get the weight where you will benefit from it every trip.
Aside from that, we all want our trucks to be balanced and skip over rough holes and the best way to achieve that is via balance front to rear. In short, trucks are like teeter-totters pivoting fore-aft around the rear shock mounts and links. With more rear weight, it literally lightens the front end of the truck and helps it pop and stay up.