For PHP, I've been very impressed by Phabricator's code (and the related phutils library). It's worth looking at the git commits as well to see just how clean a

For PHP, I've been very impressed by Phabricator's code (and the related phutils library). It's worth looking at the git commits as well to see just how clean and structured commits can be. I'm much more impressed by it than by any PHP framework code I've read (and I've read Zend, Symfony2, li3, codeigniter as well as custom frameworks)