Since I have the cheapest possible Utimate controller (Ultimate C, 15 bucks), and the most expensive one (Ultimate Bluetooth, 60 bucks), a quick comparison for anyone thinking about buying.
D-pad - exactly the same
L2/R2 - exactly the same
L1/R1 - on the C model, there's quite a bit of rattle because they seem slightly loose, however the functionality is the same
Sticks - the C model has regular Alp potentionmeters that could develop drift over time, however I was surprised to find out there's no deadzone like on most cheap models. A big plus there (could also be a downside that makes it more prone to drift, but time will tell)
Face buttons - stiffer on the C model, it's down to personal preference, tbh I like the feel on the cheaper model more. Obviously, the layout is different
Customization - none on the C model, full on Ultimate Bluetooth (deadzones, triggers, macros, buttons etc.)
Weight - the C model has no battery, but it does have vibration motors that give it just enough weight not to feel like a cheap plastic toy. Much better than cheap shit like Logitech F310
Feel in hands - pretty much the same, the cheaper one also has textures grips to make it easier to hold
There you go. If you don't care about Switch support, hall effect sensors, connectivity options, or customization and just need a cheap controller, C might seem like a good choice. Especially since you won't find anything better for 15 dollarydoos, probably even on the used market. Can recommend. The biggest downside are the hideous color options: lime green and pink. But you have to sacrifice something, I guess.