Body & susp is all an opinion on what you want to do with it. With both installed, you can get the bigger tires under it a lot easier. W/just one or the other lift, you are limited as to what size tire you can go with. If you are wanting to get offroad performance out of this, I would go susp. first and then body.
Any of the three companies have very good systems. Duff seems to be a little more proud of their stuff than the other two. Besides, you can get new leafs from WH for the same price as an add-a-leaf system from Duff. BC doesnt give a full "system" price on their site, but I would be inclined to call them and ask what their comparable equipment would run. But either way, I would say go WH or BC for your susp. lift. There is your more bang for the buck, but that is my opinion.