We have a JKU and after much deliberation went with the Teraflex 3 inch Outback suspension with the Alpine fully adjustable control arms. Also the Falcon 3.3 adjustable shocks. Night and day difference from factory for sure, 90 percent of this is the shocks in my opinion (They do not do anything for load capacity, just ride quality) We are running 35 x 12.5 BFG (true size 34.5" I would not go any taller without changing driveshafts as the front is about maxed out with the factory rezeppa joint with the 3" lift. and steering geometry changes fast once over 3" on a JK. We are fully loaded 24/7 and therefore did not want dual rate springs. (dual rate springs have a lower spring rate 'soft' section that gives you a nice ride when empty and the rest of the spring takes up the work when loaded down, single rate springs maintain the same spring rate throughout the travel). Two areas on our JK at the rear have potential for rub depending on the trim and options the Jeep has. We have factory rock rails and metal rear bumper, both extend much closer to the tire than I would like, It is possible to trim a bit of the slider off and still get the end cap back on, but there is still a pinch seam behind the slider that will dig into the tire at some point. (adjustable arms can move the axle back a bit if needed, just watch the angle on the spring and driveshaft length) the bigger problem is the plastic end cap on the bumper that flows into the stock plastic fender, full compression to the bump stop causes some rubbing there. Now that we have ditched the plastic fenders for some full coverage aluminum ones there is much more room in the wheel well and we plan on removing the end caps and installing mud flaps up tight to the exposed opening on the rear bumper where the end caps were.
Our JK is just a bit over 6,000 pounds with equal weight on all four tires. we have about 220 pounds on the roof including tent, rack and awning, which you can definitely feel. Added a heavy duty trackbar on the front and rear, Hellwig sway bar on the rear and running the shocks on firm for highway travel greatly improved its manners.
Strongly suggest weighing all four corners of your rig in both normal and loaded configurations and then provide that information to your suspension company of choice to see what they recommend. Now that we have run ours for a while, I am planning to talk to some spring suppliers and see about getting an increased spring rate for the rear and or a slightly longer spring. I could add airbags but do not feel they are suitable for long term loaded off road conditions. if you run heavy a lot, need to keep an eye on the rear upper spring perches on the JK's as they can get some cracks if bottomed out a lot.
Super happy with Terraflex so far, they have great service and seem to build a great product, only issue is the rear springs not quite enough for my particular use. I do believe that Clayton might have a slightly higher spring rate but not sure. A lot of 'lift lit' companies do not provide the actual spring rates for their products, and were eliminated from my search..