To echo what others have said, I've been evaluating many of these for the past couple of weeks... my results so far:
Homesite is my favorite and what I have been using a lot recently. I hear more/better PHP support has been added, but I found a bunch of nice free plug-ins to do a lot. About the only thing missign is support for a PHP debugegr... but with the free PHP add-ons, it is a REALLY powerful, polished tool. (Auto-complete! PHP function hints! Sweet!) NOT buggy... big plus there ;-) Biggest missing thing: PHP debugger (maybe's that's been added/being added?). Made by Macromedia but aquired from Allaire. About $100.
Dreamweaver seems like a lite version of HomeSite married with an HTML layout tool (ala Adobe GoLive). I haven't spent much time with it, but it is also made by Macromedia so I expect it's very similar to HomeSite. More expensive. Would love to know if the HTML editing side is as robust as HomeSite-- if so, that makes it the ideal choice, since the HTML layout tool would just be a plus at that point. (Anyone know how they compare?) Haven't used Dreamweaver much though I have it here.
PHPEdit is free (search Google), from France, and buggy. Some PHP debugger support. Check it out for yourself or better yet, help them bring it more up to speed ;-)
PHPEd - haven't used it. I know it's expensive (US$249) but gets good reviews. Built-in PHP debugger is a big plus. Need to do the free evaluation. Would love to hear from others using this.
The next tier down is what I call "high-powered text editors" like TextPad. Not always just for programmers but often with a lot of nice features specifically for coders. TextPad is nice. UltraEdit is what I used for years and it's VERY good, and also has a fair amount of coding-specific stuff built in. Light PHP support but nothing supercool (like auto-complete). Fairly bug-free and reliable, lots of add-ons. Excellent general-purpose editor.
Then at the bottom is Notepad/Wordpad. You can always do better than these!
Hope this helps.
-Eric
http://ericmueller.org