I personally use Dreamweaver. Zend's editor is nice too though. http://www.zend.com/products/zend_studio
I'll go for editplus, two features that I like a lot is it's ability to open many many files at once. And the second is it's advanced multiline search and replace feature.
I use Zend, PHPDesigner 2006 and Eclipse. Zend and PHPDesigner are my favorites though. I definitely can't stand writing code in Dreamweaver though... I love the product but hate writing code in it and don't like the code it produces.
phpdesigner is good - it's version 2007 now there's a paid and free version - do a google on phpdesigner...
Dreamweaver is my standard Dev choise when not in VisualStudio. Normally I would say notepad... but I get too pampered with color coding. If i could only color-code Notepad
zend is the best, dreamweaver is for design, if i want to do something quick and simple i'm using editplus. i often use smarty template engine for my php websites, i code the templates in dreamweaver, and the php pages in zend.