Franz is right, it all depends on what you want. For me, the following reasons were important:
- Open Source
- Active user community
- Ease of developing new features
- versatile
In the days that I made my choice for a CMS, Joomla! was the #2 in terms of installations, behind WordPress. The openess of Joomla! was the key decision point for me that made the balance in favor of Joomla!
You may also want to read the article
websitesetup.org/cms-comparison-wordpress-vs-joomla-drupal/
Best regards, Paul