I'm starting to wonder if all the design differences are just aesthetics? The only force being applied to them seems like the upward force from the spring and welding just locates them.
I would say it's maybe so one can't say they other stole design? I really don't know. The other being what you want to look at? The one from Barnes 4WD seems to be the most intrusive since it's also for stretching.
https://www.barnes4wd.com/Jeep-TJ-and-LJ-Rear-Coil-Spring-Relocation-Kit-_p_253.html
Or these
https://www.barnes4wd.com/Jeep-TJ-Rear-Frame-Coil-Spring-Brackets_p_821.html