Which is better to use for audio, an optical cable or an rca stereo cable?

Ok, so after hooking up an optical cable from my Samsung HDTV to my Yamaha receiver I can definitively say that the sound quality is much better now, than when I had things hooked up using an rca cable. The sound is much clearer, crisper and much more equalized between my front center and left/right speakers, when compared to the previous setup that used an rca cable. While this is my own unscientific conclusion, I would definitely recommend using optical cables instead of rca cables to hook up any stereo equipment to get better sound.

It's interesting, because I had read in a bunch of forums where people said it doesn't make much of a difference if you use an optical cable vs an rca cable, but I have to disagree. In my opinion, the optical cable will give you much better sound quality.