There's no need to reinvent the wheel. I've been using CakePHP quite a bit but have found myself frustrated by it's tightly coupled nature. I'd recommend going with Zend. It's backed by a very capable and strong community... not to mention the people who are behind PHP itself.
Yeah, I've been reading up on a few of the frameworks the past two weeks. Zend seems to have my vote so far, a bit more freedom than with CakePHP and codeignitor. Besides, Zend Studio has the support for it, which makes my life just that much easier.