Both WordPress and Drupal have strong followers, and they rarely agree on what platform is more suitable for various projects. If you’re a user of one of these platforms, maybe you should eye the other? Check out the comparison over at Performancing for a great start.
I’ve just done minor work with Drupal, so I don’t know the system very well. I found it somewhat bulky though, not Joomla bulky, but still bulky compared to more focused solutions.