Symfony has one of the most active communities out of all the PHP frameworks. This is shown by the high number of commits made every day in the GitHub repo.

Symfony has a powerful built-in event system that allows you to add flexibility to applications and makes it easier to maintain the codebase down the road.

Symfony comes with a built-in toolbar that helps developers debug their applications during the development phase.

The toolbar is also extendable and new components, called panels can be added if needed to help with the debugging process.

One of the greatest strengths of Symfony is it's amazing and large plugin ecosystem, which comes as a result of it's large and dedicated community. Having a large number of plugins means less development time and more productivity.

Symfony makes use of the Doctrine ORM to add an abstraction layer over the database in order to maintain flexibility without having unnecessary code duplication.

Symfony makes use of XML, YAML or PHP annotations to create configurations in order to tell Doctrine on how properties of a certain class should be.