homesite 4.5, although as someone mentioned earlier, it does have a tendency to hang on large search & replaces. I like the built-in FTP client however - with a decently quick connection you can use a remote server as your dev box with this. No piddling around editing one file at a time via cute...
I've also started to play with Maguma Studio Lite (
www.maguma.com) which looks promising, with a debugger built in etc.
It doesn't seem deperately stable however, so its homesite for me for now. Maguma are definitely a company to watch though - their (commercial) full PHP IDE looks very interesting indeed...