It depends on what you want to do:
- If you want to do an heavy J2EE app, you should use Eclipse, Netbeans, ...
- If you will mostly do PHP or Python with a bit of CSS/Javascript, you can use PhpStorm, Aptana, Sublime text, ...
- If you want to focus on frontend (HTML, CSS, Javascript), you can go on Espresso, Brackets and the upcoming TweakStyle. Each of them have a different added value depending on what you want to do.