Hey,

Symfony also has an automatic admin interface while Akelos has Sintags (rails-styled template code). The main reason I'm using Akelos is that it supports php4 also. The Sintags provides a much readable template without much overhead due to Akelos' caching. Depending on what you want/expect your large applications you're designing to have. Highly-critical, looming deadlines, or broad-range of feature requirements aren't ideal if you want to use Akelos since it lacks large documentation and the vast feature-set of Symfony.

Akelos is more of a rails-inspired framework and Symfony tries to be a hybrid of a variety of frameworks. Symfony's schema.xml seems a bit annoying, although I think it's possible to generate it via an existing database. I'll admit I haven't really checked out symfony enough, but I'm using a php4 enviroment, so I didn't really have incentives to.

CodeIgniter is good for people new to the entire MVC / framework environment as opposed to flat php files. The only problem is that there's few automation done for you. CakePHP is has more automation, but you have to hack around to implement features that cakephp doesn't already provide, like custom validation.

I chose Akelos, besides the php4 issue, is that I prefer the rails-styled syntax. I learned the basics of RoR and since my personal projects aren't critical or deadline driven, I'm willing to spend time learning the in's and out's of the framework.

Just my two cents. :)