Though precise statistics are difficult to obtain, PHP is undeniably a top choice as a Website building language. Since October 2009, the TIOBE Programming Community Index has PHP holding third place -- behind Java and C -- among programming languages overall. Regardless of the exact extent of PHP's usage, you need only consider that Web sites such as Facebook -- which manages millions of users and petabytes of content -- use PHP; workloads of that magnitude demand a serious programming language and supporting environment.
In our estimation, four of these IDEs rise to the top. Zend Studio is an excellent PHP IDE once you become familiar with the Eclipse landscape. NuSphere's PhpED is also first rate and deserves your consideration if you need a professional-quality IDE and support. If you're on a budget or you can make it without technical support, Eclipse PDT and NetBeans are exceptional tools.