cPanel is used by many major hosting companies and it offers the ability to move hosting accounts from one host to another with ease. Also it is very popular and most customers know and understand how to use the control panel. When customers are looking for a new company they don't necessarily want to learn a new control panel. I have been using cPanel for several years now and I can say that they do provide outstanding support when needed. You will not receive such important features from a free control panel.