I prefer cPanel for the flexibity of it. It's not very hard to make 3rd party modules for the user control panel as well.
I was using Fantasico with a previous provider, but found it is not very flexiable on which programs and/or software it installs. So I switched to Installatron. It handles around 50 or so programs/software. Even has the abilty to upgrade your current software as long as you have not made mods or hacks to the source code.
We use fantastico - but recently purchase some auto-installer licences and I think we will switch completely to it. It's more secure, more usefull scripts for clients and it integrades better into cpanel.