If you are considering an overland style build that will add a lot of weight (roof rack, RTT, bumpers, skids, etc.) and plan to have a fairly heavy payload as well (fridge, camping gear, etc.), then I would seriously consider the Outback Overland setup from TeraFlex over the other kits. At least for the springs.
I had a hybrid TeraFlex/MetalCloak suspension that worked really well and had a lot of travel on my 2 door JK Rubicon. However, as I started to build more for overland trips, the MC springs just didn't cut it. I lost most of my lift and didn't even have my gear in it yet. Fully loaded, the ride was horrible. I spoke to MetalCloak at length and they were no help. I spoke to ARB/OME and they very helpful, but the solution they had would have given too much lift for the weight I was solving for. I then talked to TeraFlex about their springs, got some great advice on my setup, and a recommendation on their 3" Outback springs for the rear. This solution has been excellent, no sag, my lift height was restored, and the ride improved tremendously. Pics - Difference in springs - you can see the bump-stop difference below. The MC spring is a dual rate spring and should collapse the top part of the coil. However, once I had it loaded with gear, they sagged to just about only 3 coils of travel and with the softer spring rate, I was bottoming out fairly often.
Good luck with the build, I hope this helps, or at least gives you something to think about.