In short, SCART if you have it.

SCART carries 3 different Red, Green, Blue signals, while also carrying the normal combined signal (yellow RCA). Audio is unaffected.

In some televisions the SCART input goes straight to the projection tube, so while it gets SCART input you cannot view other inputs.
Other televisions ignore the R, G, B signals, and use the normal combined signal.

So in conclusion, I recommend going for the SCART, it will give you better image, with less disturbances, and less distortions that may be caused by the signal conversions.