CentOS has become an industry standard for web hosting. Debian is a great OS, but it is important what do you plan to use it for. they have Linux Containers (LXC) for example, which are good for web development environment and for Virtual Servers.
You will get more vote for CentOS for sure.....but you may find many veterans out there who just love debian distros. So its basically how you are trained with the systems. My personal favourite is CentOS/RHEL because I am trained in that; but for my laptop I used to use Ubuntu and just love to work with debian distros as well when needed.
Toss another vote in for CentOS. Not only does it support the vast majority of control panels (cPanel, Plesk, DirectAdmin, Interworx etc etc) but they generally provide you a very long shelf life. CentOS 7 doesn't go EOL till 2024.
For webhosting business, I prefer Centos as most of the paid and non paid control panels are providing support for the same and Debian on the other hand is very good in setting up custom setups , non control panel servers and I always suggest Debian/Ubuntu for Custom Setup which do not plan to have any control panel.