There are lots of ways of choosing a CMS and there are a bewildering number of excellent ones to choose from. Even some of the ones that offer fewer features may be right for you. Probably best to have a simple set of criteria like ease of use, or ease of installation at the forefront of your mind when deciding. Most probably you will not need all the features of the larger offerings. 

There is a very useful compare tool at http://www.cmsmatrix.org and you can play with some of them for a couple of weeks on http://jcarling.com by requesting a username and password. 

Then again many people have specific needs and these can only be met by configuring open source software or paying for specific software built from scratch.