Can't speak to the ZTTO but the Juin Tech are what they seem to be stealing the design from, I've got a pair on the wife's cross bike and she loves the stopping power in the mud and wet. The GT version with 4 pistons was a little much to spend at the time. For a folder I might be more inclined to go with them.
For my kids I picked up previous generation deore brakes for around 100 a set, yeah newer is better but one generation older is still pretty good depending on need and much more affordable.