CMS are platform dependant
My favorite CMS, by far, is Joomla. There is a huge developer network, both commercial and open source for Joomla. If there is a specific function you want to include in your CMS, I would suggest looking at the add-on components and modules for the various CMS products.
Bottom line, the CMS will depend on the server that is hosting your site. If you are on a Linux host, you will most likely be looking at PHP/MySQL based CMS products.
If you are on a Windows based host, you can run a .Net CMS, or a PHP/MySQL CMS. I have installed PHP,MySQL and Joomla on a Windows Server 2003 host just fine and it runs great.
That's my two cents, hope it helps.
