shocks
Most of the cost increase in the Carli kit vs the AEV kit is the shocks. The King or Fox shocks they offer ARE much higher quality shocks capable of taking more abuse and allow for much greater valving control and fluid volume due to increased body diameters and remote reservoirs. Take a look at the shaft on a 2.5 King shock vs a bilstein shock. The difference is pretty striking at first.
I killed several (3) sets of Bilstein 5100's on my 3500 before upgrading to Carli kings. I have driven bilstein 5100's on several other vehicles with equal vigor and not killed them. I just don't think they are capable of taking abuse on a truck as heavy as a cummins equipped ram.
Speed bumps at 10mph are still pretty rough with a Carli kit with full leaf pack. Much better than stock, but not even close to a current 1/2 ton stock. Little pot holes at 25mph....still shake your truck about. Huge pot holes at 70+.....you barely notice. Speed bumps at 40, not even there. Speed is your friend with a pintop/king Carli kit. If you don't abuse your truck, I would either look at their backcountry package or one of the lower end Thuren kits. AEV may be fine, but don't go telling everyone you have factory payload and tow ratings after lifting your truck if you put that kit on!
Ultimately if you are lifting your truck, I would assume you are doing it to increase off road performance. In order to do that, you need springs that afford MORE travel. A lift kit with aftermarket springs will do this. A lift kit retaining stock springs will offer minimal if any increase in wheel travel. If you just want height for bigger tires or looks, spacers will do the trick. If you just want a better ride, get a 1/2 ton truck. They ride REALLY well these days! Any 3/4 or 1 ton truck is going to ride like **** on bump city streets no matter what you do to it.
All the outfits mentioned in this thread have great customer service in my experience.