What is the best IDE for development with CI

If paid/free is not an issue, then PHPStorm or Sublime Text seem to be everyone's favorite. Which to go with depends on whether you want a full featured IDE (PHPStorm) or a great editor that you can extend (Sublime Text).

Here's how to add Xdebug to Sublime Text.
http://www.sitepoint.com/debugging-xdebu...me-text-3/

I stay with Codelobster only because it's free and because the small amount of work I do can't justify the expense of a paid application.

Hey, don't work without a PHP debugger. Several free IDEs have this features built in. Two are NetBeans and CodeLobster. Without a debugger, it's like you're driving with a blindfold on -- you are going to crash!