JetBrains has just released version 2 of their PHP IDE, PhpStorm. I haven’t personally used it, but it has all the features you’d want in a PHP IDE, such as code completion, unit testing, version control, FTP, debugging, etc., plus bonuses such as support for editing HTML, CSS, and JavaScript. There’s a 30-day free trial available and a personal license costs $99 (US). PhpStorm runs on Windows, Mac OS X, and Linux.
As I said, I haven’t personally used it, but JetBrains is the creator of the powerful IntelliJ IDEA Java IDE, so their experience in creating good IDEs is well established.
PS It bugs me, for some reason, when the names of products use “PHP” as “Php”. It just seems so wrong!