Right now two of the most popular open source content management systems are WordPress and Drupal. WordPress is very simplistic and easy to roll out, which is why there is nearly 80,000,000 websites using WordPress. Then you have Drupal which is a more robust content management system that needs a little bit more love to get things moving.
I migrated my personal blog from WordPress to Drupal so I can have more control, from performance to marketing specific content at visitors. I'd love to do write a WordPress vs. Drupal battle blog, but I want to share how easy it is to migrate. WordPress is a great platform to start but it is not future proof for large companies, things that Drupal does provide.