On his Medium.com site Benoit Schneider (CTO of Outsourcify) has a post sharing some of the reasons they made the choice to use Symfony for their web development needs.
He starts with a bit of background on his own experiences with Symfony and why he chose it for his own needs early on. He then shares his thoughts around "why Symfony?" when there are many other major frameworks to choose from. He wraps up the post with a summary of some technical reasons to use the framework including the innovation it brings to the table and the robust ecosystem around it (and related products/tools).