From what I've seen, the eBay ones aren't so bad if you really want to save money. I have a UMI kit that came with fancier viking coilovers-- I agree the valve adjustability is nice but not needed. The height adjustability I found really useful.
Check out this video from Donut. They're a little silly and are into import cars but they do a good real-world comparison of high end vs low end equipment on two identical cars.
https://youtu.be/8kef1wXcQYw?list=PL...j2iz5pZiQl_Nba