I used to own KYB AGX with RS*R springs... at the softest setting it rode like stock... couldnt even tell the difrence... at teh stiffest. It was very responsive but no where near the performance of Coilovers.
For my purpose... recreational drift and street touring
it was good... need to be stiffer around wide high speed corners.
Along with that i had struts, sways, bushing kit, and pretty wide tires. Good cheap set up for a 1.5" drop