The downloadable extensions, free and paid. You can make your site function exactly how you want it to with as little effort as you want.

Joomla is very powerful and great content management system. I really like it for my complex projects. I must say that the extension and modules are very powerful and easy to understand, you'll learn to control very quickly. The whole web development process is simple and easy while on Joomla. Joomla dashboard is pretty simple and neat and clean interface, you'll learn to manage the end product very fast due to clean GUI of this magical CMS. I. Really love the themes customizations as its simple yet you get powerful editing tools handy. For me it's my second best CMS after WordPress or I must say for complex projects it's the one and only tool I ever used. It's really easy for me when it comes to search engine optimization, e-commerce solution on the other hand you'll use powerful extensions for free. It's really easy to track content while on Joomla.

It's generally faster than wordpress, more secure and with more features built into the core.