First, freeBSD and Red Hat aren't control panels. Those are operating systems. Of the two I would certainly suggest Red Hat for a newbie.
Of these 3 control panels: CPanel, Ensim and Plesk- I would think CPanel is the easiest to use and has most features. However dont necesarily take my word for it, as I havent kept myself up to date on ensim or plesk Another fairly easy to use, and great looking control panel, is Direct Admin (which I currently use myself). (look around on the respective control panels homepages, you will probably find demos you can try out)