ksc are sometimes plastic as they are for the Japanese market.
Kwa are the US marketed ones that will be better. they shoot just as well as tm pistols. I see tm hicapas jam up all the time, my Kwa atp has never done so.
I do aipsc so these pistols go through a lot of wear and tear. works in freezing temperature and out ranges most aegs, including tm ones.
tm work well because they are plastic and have good hop units.
Kwa pistols work well because they have a better gas system, which allows them to stay on par with tm, while keeping metal slides. hop units work nearly just as well, just slightly fidley to adjust without the key.
I go Kwa everyday. fits real holsters, works in cold, metal slides.