What is the best slideshow to CCK image field?
Well, there is of course this page in the drupal docs: http://drupal.org/node/418616

Unless you have a very specific use case which can be accommodated by a specialized module you really should go with the views slideshow module (http://drupal.org/project/views_slideshow). Very well maintained, fairly well documented (but a lot of tutorials flying around) and a lot of modules integrating with it. With this module you can do almost everything slideshow-wise but it might be a bit complicated (but again: lots of tutorials available).

You can of course check out some of the other modules if they offer something more matching to your specific needs.