There are several leading open source content management systems, each has its advantages and disadvantages. FSI builds websites in WordPress and Drupal.
FSI has developed dozens of WordPress sites (including this one) and provide a quick and inexpensive website for clients that they can maintain for themselves.
Check out FSI WordPress sites
Drupal is a more robust system to maintain content and documents. It is, however, a more difficult and time consuming (read… “expensive”) environment so it is a better choice for sites needing complex document management or taxonomies.
For example, local government websites need to track minutes, agendas, forms and other documents along with may departments, boards and committees. Drupal is the better platform for local governments.