I have a Draw Tite "remove-a-ball", the reese rails, and a B&W in my TopKick.
The Draw Tite serves its purpose, but is not used that often because it is a 6 liter gas plow truck. Why use it when there's 2 or 3 diesels there at all times.
The rail system has been in my last 2 duramaxes. It has done me well, and hauled large loads from Michigan to Florida and Jackson Hole, but I noticed this year it was getting sloppy.
I love the B&W in my TopKick, and am considering one for my new 6.7 Superduty I got last week. I will say that it took a torch to get the ball out of the bed when I bought the Topkick last year because the previous owner had never used it in 4 years.