ATI CCC pixel format

RGB 4:4:4 Studio Limited works best for my Yamaha Receiver since it clips BTB and WTW.

YCbCr 4:4:4 should be best for videos as it provides 16-235 levels and YCbCr is what is used for videos anyhow (BluRay, etc.). Conversion to RGB is unnecessary. RGB is really for PC (games, etc.).

RGB should yield better results. Even though the component formats "should" be better for video, the concensus is that all of the video processing is done in the RGB space so you are adding 2 extra conversions by selecting YCBCR format. Meaning YCBCR video is converted to RGB, processed, then converted back to YCBCR if you select that format.

The Blu-Ray data is YCbCr 4:2:0, but it's rather obvious that internally the data is converted to RGB first and then later back to YCbCr, which is a usually not a good idea if you care about max image quality. So the only true choice for us HTPC users is to go RGB. (I read it here.)

Video disks usually contain YCbCr 4:2:0 16-235 in compressed form.

Displays Probably use some RGB 4:4:4 representation internally before driving the physical display.

The conversion must be done somewhere. Where best to do it? Perhaps depending on the quality of conversions in either unit. In practice that is a small factor. A much bigger factor is that these things tends to be buggy, poorly documented, and one choice may be better calibrated out-of-the-box than others.