Laravel

Framework with expressive, elegant syntax.

Phalcon

The fastest PHP Framework.

FuelPHP

Simple, flexible, community driven PHP 5.3+ framework.

Yii

High-performance framework best for developing Web 2.0 apps.

Zend Framework

The most popular frameworks for modern, high-performing PHP applications.

CodeIgniter

Easiest to learn. Easiest to master. (This site is built with it)