The differences are subtle, but they are also designed for slightly different applications.
From a hardware/system standpoint, and according to their website, the AEV lift uses progressive rate springs and shock absorbers that are "tuned" to the spring rate. This matching of the shocks can be very important to how the suspension functions as a system. The suspension engineer that started Nth Degree Suspensions (now owned by AEV) was a former Jeep engineer, so theoretically he knows their system very well. The AEV kit is also fairly complete and can be run as is. The AEV kit is designed for primarily road use, but is fully trail capable.
The Teraflex and Rubicon Express lifts are off-road first, but road capable. They use linear rate springs, and it's not clear if the shocks have been re-valved to match the spring rates. The Teraflex and RE kits are somewhat complete, depending on which kit you buy.
All three of these kits have their proponents. However, if you are primarily road bound, then the AEV kit seems to be the best fit for your intended use. I would also suggest you consider adding AEV's geometry correction brackets to any of these kits if you don't get adjustable control arms.
2013 JKU Sahara, Commando Green - 3" Franken Lift w/ Fox 2.0 Res shocks - 36x13.50 17 Irok Bias Ply on Cragar D Window Rims - Check out my Jeep Blog at Sand, Mud, and Rocks Off Road http://www.smroffroad.com