CLPV is CyberLink Pano Vision technology. It is a non-linear stretching technique that adjusts the viewing ratio of the displayed video with minimal distortion. It achieves this by stretching the video image on the edges of the screen, leaving the center of the screen unaffected. I think the other methods are straight forward in verbage.
There is realy not a best, it depends on what you are doing and the desired outcome.
Jeff