Probably nobody will say you, which one is the best. Nobody has enough number of new cameras to compare themselve. You'd probably have to read about their parameters, decide which ones are the most important for you (HD? Long video? Resolution?) and then check, wheter CHDK supports specified camera.
CHDK posibilities not much differ between each camera. Only sometimes something just can't be done on one camera. I suggest you to ask on appropriate camera thread about camera you might be interested in.
CHDK helps not much in video recording itself, but there are a few scripts and possibilities of zoom, maual focus, quality override.
