What are you going to be using them for? If autoX is in there, the Z2 will be phenomenal. I have the Z1 and they're not very noisy. I've never run them but have heard the KDW2 are noisy.
Don't get the RS3, scary in the wet. Take a look at the Hankook ventus v12, great for DD with the occasional autocross. You probably won't see the limit of those on the street.