I personally use many many editors.
Zend Studio :: Used probably 80% of my time. Easy project creation (once you learn how) and awesome PHP help & syntax checker. Works nicely, and is a fork of eclipse (though that is a drawback).
NuSphere PhpED :: Used whenever I get tired of Zend Studio. Not as good of features, and has its own debugger; however, it does have integrated Database, FTP, SSH and other tools which are nice 😉
ActiveState Komodo :: Used sparingly, but it is a good IDE. I just couldn't get past a few of the bumps that they haven't fixed like collapsing code and minor minor items. Otherwise, very good product. There is an "open source" edition which is free.
Blumentals WeBuilder :: I used to use this; however, I dropped it when I got my real PHP job for Zend. It's nice, and doesn't cost much. Did what I wanted (CSS, HTML, PHP, Javascript) and was pretty fast IIRC.
Edit+ :: Still my favorite quick-edit text editor. Supports multiple languages (Java, Javascript, C, C#, C++, PHP, CSS, HTML, XML, etc.) with syntax highlighting and custom clip-texts 😉 My first real PHP editor, and still, I believe, the best quick-editor out there 😉 [Cost: $20]
And of course, I do sometimes use notepad++ whenever I feel the urge to not use Edit+ (which is rare) or if I feel Edit+ is getting slow.
Hope that helps you out somehow.