Skyjacker radius arms are not square
Skyjakcer radius arms are very very tough
The Skyjacker transmission crossmember is so so, meaning it hangs low in comparison to the James Duff version and its a round tube, so if you dent it all strength is lost. With that said I have not made a dent in my Skyjacker setup and it has been abused.m Skyjacker radius arms are made to be used with 4-8" of lift, they work very well with rubber bushings and they fit perfectly every time.
The James Duff classic style radius arms are nice, but we have had some trouble fitting them onto Explorer's They are also made to be used with 2-3" of lift and their shock hoop.
The Duff transmission X member is really trick and is tucked up nicely under the truck
The Duff new Heim style radius arms use a single tube, which has been tried many times before, but so far I have not heard of these new ones failing.
They again are designed to be used with 3-4" of lift and the Duff cusom coil bucket and shock hoop
As Froader said any extended arm is likely going to allow you to reach your maximum TTB travel, unless you go further and run custom steering and beams...so price and lift height would be a good place to start.
I cant say enough about Skyjacker products. Over the years I have seen Rancho arms fail, I have seen Superlift arms be re designed 3-4 times because they had design flaws and also would fail, I have heard about issues with the Duff suspension parts fitment, but never really their strength. The only disadvantage we have found with teh Duff products is that with over 4" of lift the radius arms just dont cut it, they dont have enough caster built in, on my friend truck that runs 6" lift coils and the Duff classic arms mounted to custom beams, we had to flip the Duff arms side to side and run them upside down.
I have never heard these complaints about the Skyjacker TTB stuff nor have I seem their radius arms fail