As a open-source company that offers web solutions to our clients we have tried both Drupal and Joomla. There are some things I would like to point out. Though both are great systems for content creation and management, I feel Joomla excels when it comes to updating the system. Joomla developers take pains to keep updates as simple as possible compared to Drupal.
To read update documentation about Drupal seems to be a nightmare for Joomla developers, they simply don’t like to run the update.php each time. Joomla they say, all we have to do is to download the update files, detar (uncompress) it and upload it to server.
When it comes to usability Joomla is far better for end user. When it comes to ease of developing, Drupal rocks. We are awaiting for Joola 1.6 and wonder how difficult it would be for us to update our Joomla installations. Joomla team is working hard to kep installation as easy as possible. Many of our clients businesses run on Joomla. This major leap from Joomla 1.5 to 1.6 is going to be cool.