Joomla! is used by our IT division to rapidly develop dynamic sites according to the needs of each department of the company. We tried to use WordPress but realized that when we had to develop something different from the focus of blogs, WordPress did not meet us and we had to migrate to use Joomla!. We had no problems using Joomla! here.
Joomla has a more general and wide use, more documentation, forums and community that develops many templates and extensions for almost all purposes. It has a great web-based administration environment and, with the correct permissions setting, it can be prepared for a regular user to submit content to the site autonomously.
When you need something done quickly and automated and with good looks and experience for the user, Joomla! is the best option. For other more specific purposes like an e-commerce site, other tools should be considered such as OpenCart and Magento. It is worth mentioning that even e-commerce sites can be made with Joomla!, using a component called VirtueMart, but we did not feel much security in using it, but that seemed very good too.