We really prefer cPanel for a several reasons, notably because of how much other companies use it.  The commonality of cPanel among hosting companies combined with the fact that it is very easy to use make it almost a standard.  Many people are already familiar with cPanel, and if you are not it’s pretty intuitive and easy to use as well.  Additionally, cPanel is overwhelmingly unrestrictive, and will let an administrator make almost any change he or should would like.