CodeIgniter is for me the PHP / MVC framework of choice but it is preferable to add an extra layer.
I've chosen CodeIgniter because it's easy to instal and set-up, it's light and it's well documented. However, it's missing some functions and in pacticulear logins and roles management (as most of applications needs an authentification).
Here are a few libraries to improve CodeIgniter :
only for logins management
Does more than login management: Administration, modules, database management and backups, themes and emails sending ... There's a presentation on slideshare.
It's more a CMS easily editable than a framework.
Is a CMS but also a framework with a lots of extra functions: modules, data migration ...
For now, I've chosen Community-Auth as I don't need anything else than logins management. For another project, I will test Bonfire or even FuelCMS.
Happy coding ! !