I went with IronMan Fab 4x4. Upper and Lower on the front have Currie Johnny Joints, the rears do not, they are all adujustable. IronMan makes a hell of an arm. Really beefy, great customer service, well built and it's a small shop in NC so it makes you feel good when you order :)
THe Currie joints are the main theme. The stock arms are thin and have bushings. THese bushings wear out over time. As it is designed from the factory, the stock arms are not made to handle the strains induced from an articulating axle. ASide from the fact that they are thin and lightweight, the ends (where they mount to the axle and frame) do not allow for any movement or transfer of stress. This means that all the strain created when moving the axle is transfered to the mounts and likely the axle as well, depending on how articulated or flexed out the axle is. The JJs eliminate the problem by swiveling which helps the axle better articulate and doesnt transfer stress to the mounts or axle itself. In my opinion, new arms are useless if they don't have some type of swivel joint on both ends of the arm. There was an excellent write up/debate on JeepForum on this very topic. A proper arm is beefy/strong and is equipped with a swivel type joint at both ends-otherwise you're not gaining much other than it being a bit thicker. Currie, Clayton, IronMan Fab 4x4 all make top notch arms. JKS has good reviews, but I can't remember if they mount JJs on both ends or not. Rough Country offers their X Joint (i think thats what they call it) which is their version of a swivel joint. However, they are only mounted on one end and therefor don't completely solve the issue, so what's the point?
As for the arm being adjustable: I found it helped in my axle swap with setting the pinion angle correctly and if i am not mistaken, they would come into play if i were to change my suspension height dramatically. With the IronMan i could actually set up a medium length arm if i dialed them out.
