I just took delivery of a 2017 F450 with the factory 5th wheel prep kit and the Reese Elite hitch. I've not towed with it yet, but it looks like a quality hitch from what I've read. And since I got $6000 off the truck, I figure I saved some on the hitch as well. I think if you buy an equivalent hitch aftermarket, it's going to cost at least as much as the Reese, probably more.
The cam system is pretty slick. From what I've read, if you do it after the fact, the dealer has to lift the bed off the to install the cross member supports. That's not a cheap process. So much better to do it as a factory option.