One of the most frequently asked questions we get is: “What’s the difference between Drupal and [another CMS]?” Well, according to the Nonprofit Technology Network’s 2008 Content Management Systems Satisfaction Survey, the difference is that Drupal is the best. Industries heavily represented in this survey include education, science and technology, and, health care.
In a survey of over 1000 members of the nonprofit technology community, Drupal came out on top as both the most commonly used CMS and as the CMS with the highest grades. As many organizations reported using Drupal as reported using Plone and Joomla put together. Drupal also scored As both for value and for quality and reliability. Open source CMSs as a group beat out commercial solutions.
You can download the original NTEN report here (free for members only): http://www.nten.org/research/2008_cms