It is not a discuss of the best features for development, it’s a review of most suitable IDE for comfortable work.
Most of developers I know after numerous attempts to choose appropriate IDE finally settled on this one. It has everything you need to build wonderful WordPress sites, themes and plugins. Also it’s WordPress integration is just perfect! I almost has syntax highlight for WordPress functions. There are so many necessary tools and features: autocomplete, fantastic intellisense, terminal, FTP, refactoring, database support, version control. And of course your debugging will be perfect if you will install the XDebug in PhpStorm and for your browser too.
How much it costs: PhpStorm firstly I get a free 30-day trial and then you can buy a premium version differential, that cost depends on the period of usage.
How much it costs: Aptana is free and open source.
In fact, NetBeans supports not only web technologies, but it’s good for Java, C/C++ and others. It has all necessary features: autocomplete, inline validation, refactoring, syntax highlighting, debugger and easy project management. It has powerful worldwide community and a lot of plugins for comfortable work.
How much it costs: NetBeans it’s free and open source.
This one is not a IDE, but it’s very useful text editor for coding you probably can use everyday. It’s easy, simple, has portable version and exist required everyday features: syntax highlighting, autocomplete, multiple selections and many other helpful features. It’s Goto Anything tool skips you down to any place in your file and Split Editing tool is very useful when you need to edit different locations simultaneously in one file or even provide multiple editing in multiple monitors.
How much it costs: Sublime Text has free trial and premium version for 70$.
These are some most popular and convenient IDE for WordPress development, but everybody have our own preferences. And maybe you work on IDE, that isn’t mentioned in this article and your IDE is comfortable for you. But who knows, once you may try one of these ones and will never back to your old IDE. Have a great coding!