We’re re-building our web development solution for multiple projects from the ground up and we’d like to know your thoughts on which is the best future-proof, tried and tested PHP5 framework out there.

We want something that’s very flexible, OOP based and Ajax happy. Anything that comes with things like CMS components (or class libs) to make development quicker is a massive bonus also, though we’ve various in-house bespoke CMS systems we’ll need to integrate too.

As ever, whilst we could just go ahead and try a few out [and are doing] it’s going to save us an awful lot of testing time/fumbling about if there are some of you out there who’ve had the chance to work with these frameworks to know which is the best! If that’s you or you have any comments on this please post.

Here are some we’re definitely looking at:
http://seagullproject.org/
http://codeigniter.com/
http://framework.zend.com/

Also is there anything missing from our list of best players above? (apart from CakePHP)