Red, Green, Blue (RGB)

Term used to describe systems that output or transmit separate colour signals for the 3 colours that make up a video signal
The SCART connection which is used in Europe can carry an RGB signal
RGB is a huge improvement from composite

As to whether RGB or S-Video is better in the average set-up depends on the users equipment (Some TV's don't work all that well with RGB)
Convenience also plays as factor as not many AV amps/receiver on the market have SCART switching, but most have S-Video switching (Can be an issue if you have a lot of video sources to wire up to a TV with just 2 or 3 SCARTS)