In compare with Joomla, Drupal has active community of developers, who constantly come up with new features, upgrades and up-to-date security measures.
Joomla may be a suitable solution when you do not plan on expanding or upgrading, but once your project gets bigger, Joomla is no match to scalability of websites that run on Drupal. Using Drupal also provides you with more security measures than Joomla.
Our team of developers is capable of making a safe migration from this open-source CMS to Drupal.