If you want an aesthetically pleasing but ultimately utterly useless replica, then yeah, KSC all the way.
It's realistic to the real one, but good GOD the gun is terrible. Weak recoil springs mean the slide takes a good two seconds to return to battery half the time, the safety is finicky and breaks easily, and the whole system is essentially the real gun's workings, fiddled slightly for airsoft use. This is fine in a real gun, with a huge hammer spring, but utterly useless in an airsoft gun. With any sensible hammer spring, the gun simply light-strikes 90% of the time, and with one stiff