Sublime Text has got to be one of the most popular text editors out there for coding. Although still in beta, Sublime Text 3 is a relatively stable and very usable. I’ve personally been successfully using it for over 2 years now both at work and at home. It’s sophisticated, lightweight and easy to use. It also works on all the major platforms: Windows, OSX and Linux.
Sublime Text is not quite an IDE (Integrated Development Environment), but with the installation of a handful of packages/plugins you can really make it the ideal editor for developing PHP in.