There is much debate about which Content Management System (CMS) is the "right" one to use.  My blanket answer is:  It Depends :)

The key to selecting a CMS is to evaluate the functionality needed for the website, the project budget, and the ease of use for both admins and content publishers.  A big plus is to acquire a CMS that is open source, meaning that custom modifications can be made to the source code in the event that the CMS does not offer the functionality needed "out of the box". 

When evaluating a CMS, the first thing I consider is the web server that will be running it.  Some CMS's run natively on Linux/Unix servers and are at their best in that environment.  The next thing is to look at the website's functionality.  If the site will be for personal use or blogging, consider Wordpress.  If E-Commerce functionality plays a role, be sure to look for shopping carts that integrate with your CMS.  Another issue is theming or skinning your site.  I suggest looking at what it takes to create...