Its called research guys. Not because someone told me.
AEV is the lightest lift out there, with potentially more engenieering in thier product than anyone else that just bolts into the stock locations. AEV's kit has been well documented. Their kit adds zero unsprung weight, addresses the suspension and track bar geometery to maintain the "best link geometery" in the industry. I will agree that their drop brackets are questionable for a lift that is going to see a lot of time in the rocks. But really? We are going to bash the drop brackets but not bash the stock brackets that everyone else is tieing into?
AEV also uses the stock arms and bushings. Again, no addtional unsprung weight, the bust bushings to use to isolate road vibrations, etc. In my opinion, and based on the OP, this would most likely be the best kit for the OP's requirements.
Tera, is going to give the best of both worlds. I would toss several other vendors in here as well. DOM tube, Clevite and Speherical Rod Ends. More unsprung weight then AEV, but more durable arms. The geometery for the arms is now changed, not alot, but they are. The more the arms are moved from the horizontal plain, the more you start to experience greater suspension movement under normal driving conditions and the arms will want to move down and act as a lever with every bump. With the bushings that they use, you get a compromise between on and off road performance by maintaining some vibration isolation and increasing flex.
RK has the heaviest lift out and the least vibration charaterisitcs with the bushings that they have choosen to use. Potentially the best flexing kit out there right now. However, this is the heaviest suspension and larger portion of unsprung weight of any kit. All that leads to the worst On Road experience of any kit listed. Heavier control arms, with the geometry being changed by lifting and using the stock locations is going to allow the arms with every impact, a greater ability to push down and want to rotate the axle under instead of pushing into frame. And I still haven't addressed what the negative impacts that unsprung weight does to things like braking and steering and cornering. I would like to see the RK 4" kit go head to head in an On Road course with the AEV kit. Again, the AEV and On Road testing has been posted on here, and in many other places.
That being said, the RK kit will offer you (of the three listed) the best off road flex. Since the OP defined the experience he was looking for, I would suggest AEV. If they need a good compromise, I would look at more durable, but lighter suspension and make trades on both sides.
In order of upgradibilty as I have dug around, AEV has the least, Tera/Poly (for you Pig) and RK all seem to have a fair amount of upgradibility built into thier kits. But not everyone wants to continually upgrade crap and has no need to try and be the coolest of the cool and really just wants the best working solution for thier needs.
Maybe some of you forum jockeys might figure that out someday.