There is no advantage for any of the bodies for rate of feed when using a force fed hopper. When using a non-force feed hopper, the powerfeed body or a center feed body with a tall ball stack is preferred.
The center fed body allows the hopper to be balanced over the center of the gun and makes it easy to shoot both right and left equally. The disadvantage is that it blocks you from sighting down the barrel or using open or red dot sights. You can use occluded sights on a center fed body though. You don't need to worry about an elbow twisting or breaking causing your hopper to move around sideways.
The standard feed body places the hopper out to the side of the gun which makes it unbalanced and you have to deal with elbows that could break or become loose. The center of the body is clear of obstructions for easy sighting and shooting but the hopper sticks out to the side which makes it hard to shoot from your off hand and still stay behind cover in tight situations.
The powerfeed body clears the center of the body to allow you to sight down the body, but not enough to allow you to mount a sight unless it is high enough to clear the powerfeed. A high sight does work quite well actually. I used to use a red dot sight on mine back in 1993. Its great for aquiring a quick sight and eventually your muscle memory will kick in and you won't need it. You do need to deal with elbows that could break or become loose. The hopper is more centered than with a standard feed but may require some tweaking to get the hopper directly in the center of the body for perfect balance depending on the elbows you use and may require you to cut the feed tube.
Except for the Automag in front, its usually the man behind the equipment that counts.