Fortune Auto isn't even in the same ballpark as either Bilstein or RCE/KW. Seeing them in the same sentence is sad and weird. Fortune Auto does do a few things correctly:
1) They are revalvable and correctly valved for the selected spring rate
2) Rebuildable
3) Option for Swift springs and radial bearing spring perches
On the flip side, though, the actual components are primarily sourced from the same Taiwanese manufacturer that makes most of the other budget brands, although they are assembled in the US. Additionally, their damping design is not application specific (shared shock cartridges), and it is 3-piece design, which is not the best design choice for performance and is focused on cost reduction above all.
Meanwhile Bilsteins and KWs are 2-piece designs (single perch) with application-specific shock cartridges, valved to match the springs they ship with (in case of Bilsteins can be purchased valved to match Eibach springs), and are manufactured and designed in Germany out of high quality components.
Flex Z's are not on the same level as the Flex As. Flex Zs are clearly a much lower tier product from Tein's lineup. Some Tein stuff is amazing (SRCs), some of it is trash (Basis Z). You pretty much get what you pay for there.
BC Racing has their own facility in Taiwan, rather than being just one more brand on top of the same coilovers ala Megan Racing, D2, KSport, Godspeed, Truhart, et al. Technically, if you want to get really nuanced about it, BC Racing products are slightly better than their Chinesium peers, but in the big scheme of things they are still utter and complete trash.
Raceland is actually even worse. It's basically the absolute bottom of the barrel. Any time I see someone buy Racelands I literally cringe. If you're going to buy into trash tier parts, at least get the top of the garbage heap and buy BC Racing.
ST coilovers are fine, but suffer the same problem you run into with KWs generally (which is why the RCE versions are better), in that they are not revalvable, so you need to be careful with spring selection, but if you pick the correct springs they work fine. This really only becomes problematic if you need to change spring weights for some specific reason, otherwise they are valved to match the springs they come with. For many users this is probably fine.
If all you care about is slamming your car with tilty rep wheels for instagram likes and fuccboi points, then you can absolutely buy the most garbage coilovers available because it doesn't matter. But if you care about performance or ride quality you are literally throwing money away by buying trash parts, as you'll end up needing to replace them anyway and the entire time you'll have a less enjoyable experience driving your car. Buying quality parts pays dividends, so instead of cheaping out try saving up. Your car does not /require/ coilovers to drive down the road, so save your pennies and then buy something that doesn't suck.
If your budget isn't flexible, as I pointed out before your experience will be better with good quality lowering springs on factory dampers or on quality aftermarket non-adjustable dampers with appropriate parts to allow for a good performance alignment (camber bolts + rear LCAs) vs buying "budget" coilovers. I would take the RCE Yellows on PP Sachs dampers w/ Whiteline camber bolts and an SPC rear LCA (about $600 altogether) over any coilover you could buy made in Taiwan for both street and track usage.
This video covers pretty much what you need to know.