It is undoubtedly Joomla. It is well SEO ed. Then stands Drupal. Joomla is the best one because if it would have not there then there would be no Boddunan(as it is also developed in joomla).
Joomla is the best because this system includes features such as page caching to improve performance, RSS feeds, printable versions of pages, news flashes, blogs, polls, website searching, and language internationalization.
Use Mambo(Joomla) when:
* you don't know about the tech stuff at all
* you want easy install & setup with your mouse
* you don't want to learn the tool you're using
* you don't need to integrate other scripts etc. to your site
* you want a candy site and don't mind several other sites using the same template(s)
* you don't need SEO out of the box
* you don't care about server resources
* you're running (or planning to to run) only one or max a couple of sites
* you don't need one log-in to several sites
* you don't need user groups & permissions
* you don't run membership site(s)
Use Drupal when:
* you want a rock solid & high quality platform for your sites
* you want or need a real multi-site-feature (only one installation for several sites)
* you need any kind of user groups & user permissions
* you need to run also membership- and community sites, not only CMS etc
* you want a Powerful templating system
* you're ready to invest a bit of your time in order to realize all the huge possibilities of Drupal
* you understand the meaning of clear, high quality code and API (easy to integrate with other solutions etc)
* you want flexibility and don't like limitations
