I used jedit as php editor of choice for quite a while. Although it is java-based, its features and plugins make it suitable for php as well. Additionally, its not very large, and it is quite suitable for php editing jobs

What I like most, many of the useful stuff is available as plugins. Without them jedit would be unusable in my environment where I have to access files through net, both SSH1/2 or FTP. This is a great bonus. Also, split screen feature, various modes for search really help in development. Even more so, it is completely free.

However, there is a small catch. If you use jedit with FTP/SSH module, it is good strategy to kill ssh processes occasionally, or you can use up your server memory. Havent seen this behavior with other editors.

Overall, if you want a completely free tool, Jedit is way to go. If you hate java or want standalone, faster applications, you should look elsewhere probably.