From my experiences, I wouldn't say that copper is better, but different. Copper tends to be warmer and richer, while silver tends to be more revealing and transparent. I prefer the sound of copper myself, but I've heard silver sound good in some systems, mostly tube systems.
Do Kimber KCAG's sound bright????
I have Kimber KCAG through out all my connections except for Transparent Audio speaker cables and PS audio power cables. My system sounds a little bright. Have Bryston amp and Adcom preamp. Is copper all round better???? Mike