Symfony: There is a ample of components in the Symfony framework and they all have a defined purpose. In Symfony, there are reusable components that are good enough to paginate, create sessions, scaffold an application, security etc. Using the components is very easy and this is one area where this framework excel.
Cake PHP: Again this is a great framework. In CakePHP the components are not limited to the core ones but can be easily extendedand is very useful in creating a dynamic application. Both of these frameworks use components to help speed the application and are every helpful even to the novice programmer.
Symfony: With websites already making use of Symfony, the community is growing like a wildfire. It is a very abundant community with many developers helping and contributing tutorials, documents etc. every single day.
CakePHP: This community is rising fast to help meet the users requirements by contributing more technical documentation, tutorials, events etc.
This is the most common question for all the frameworks. How secure is it? Even though, Symfony and Cake PHP provide good methods, components and helpers to secure your application. You just have to use these and use it correctly. ACL implementations, data validation and sanitation and much more can be used to secure the application.
To conclude, these are some of the things to decide when trying to choose a framework will help you to build great applicaitons. Some developers are of the opinion that every framework is useful but remember that the best solution to a problem is the solution that solves all of your major crux. Have more to share, then leave your replies in the comment box below.