The Laravel framework [1]. It makes the most of the latest features available in PHP (reflection, traits, namespacing, etc.) and its author, Taylor Otwell, has an almost obsessive attitude with the naming of methods and formatting of the source code. For instance, every multiline comment is exactly three lines long, and every line is three characters shorter than the previous one [2].
[1] https://github.com/laravel/framework
[2] https://www.reddit.com/r/laravel/comments/20ovey/just_notice...