When comparing Symfony vs Li3, the Slant community recommends Symfony for most people. In the question“What are the best PHP frameworks?” Symfony is ranked 5th while Li3 is ranked 10th. The most important reason people chose Symfony is:
Symfony is open source and released under the MIT license.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Open Source
Symfony is open source and released under the MIT license.
Pro Easy debugging with a built-in debug toolbar
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.
Pro Great plugin ecosystem
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.

Pro Highly active community
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.
Pro Teaches you good practices
Symfony makes you be a better programmer. You have to deal with the latest object-oriented design patterns such as service-oriented architecture, dependency injection, interface abstraction, and so on.
Pro Uses YAML/XML/PHP/Annotation
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.
Pro Powerful event system
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.
Pro Great templating engine
Uses Twig, which is a simple and easy to learn templating language that can also be used as a standalone engine, outside the framework.
Pro Uses Doctrine ORM
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.
Pro Unified relational and non-relational database API
Lithium has unified the relational and non-relational database APIs into a single one. Being one of the few frameworks to do it.
Pro Robust plugin architecture
Lithium makes use of PHP namespaces to create a powerful plugin architecture. Almost every component of the framework is replaceable.
Pro Fast Bootstrap & Autoloader
This framework loads faster than most due to its class autoloader. It is flexible as well and handles older classes - but requires the developer to define transforms here for naming convention, includes, etc. Many other frameworks use Composer for autoloading and that significantly slows down their bootstrap time because Composer's autoloader is extremely compatible without much developer interaction (it does not require as much involvement for autoloading legacy libraries). So it's a trade-off, speed vs. a little bit of up-front work.
Pro Integrated unit testing
Lithium comes with integrated unit testing. It also has a test dashboard.
Pro Aspect inspired filter system
Lithium's filter system is based on the paradigm of Aspect-oriented programming which aims to increase modularity by separating cross-cutting concerns and helping speed up development.
Pro Great for building an API
Lithium can return JSON and many other formats from the same actions that render templates increasing productivity in many cases. It handles a "type" key in the route which allows it to render various responses with different Content-Types. This is incredibly useful and easy to extend. This combined with closures in routes makes Lithium a very good framework for building a RESTful API.
Cons
Con Settings
Too many configurations.
Con Very hard to install
Setting it up on webhost without a console is difficult.
Con Promotes bad development practices
Such as annotations via comments.
Con Doctrine ORM
Symfony Standard Edition, which is the most widely used distribution, comes integrated with Doctrine, the most resource hogging ORM library.
Con You need a lot of files to display a single page
For a simple hello world page you need about 5 files.
Con Less than ideal documentation
Documentation is scattered so it takes a little while to learn and figure some things out.
