The kits are depending on what you want and what your plans are. I can do better than both those prices if you need help on it.
The rough country kit is a good kit for those on a budget and want a complete kit, bolt on and go.
Black Diamond is a division of Superlift. They make great kits and the military wrap springs are an advantage.
Both kits have a bit of a reputation for riding slightly harsh, but pretty much any arched leaf spring is going to have the same effect. I've found the ride personally to be pretty much the same as stock after the springs are broke in.