I ran the AEV 3.5 on my ’08 JKUR and loved it so much I installed one on my 2012 JKUR. I can’t speak about other lifts for the JKs because I haven’t any experience with them but it (AEV 3.5) works great off road and flexes just fine. You will probably hear about how the geometry brackets give up ground clearances and technically it does to some degree, but I have yet to make any contact with them even while doing limited rock crawling.
The only negative thing I can say about the lift is that they started shipping with a gas charged stabilizer shock. Running it can cause the steering to have a very slight pull to the drive side. I took mine off and reinstalled the OEM shock and it handles like a charm. Their coil springs are amazing too.