I started using PhpStorm and I like it. I am still on trial, but I think I have enough reasons to make my boss buy the licence for me. Well one little shortcoming came on the way, I had 4GB of RAM which runs on fumes at the moment. Next week 8GB upgrade should arrive and I should be just fine. Basically I like everything about it, well maybe only the fact that it's written in Java, but so are they all. It performs very well with external sources which it is the case for me most of the time. It downloads the sources and syncs the code. You can set it to automatically sync and show you diff for merging when it has issues(I prefer content comparison, that is an option with PhpStorm). Using terminal through the IDE is also more pleasant than in other IDEs I have tried(Aptana 3, Netbeans 6-8). It has every tool you need, version control, auto-complete, etc. It even has Drupal coding-standards and other Drupal related configurations it it by default. The most important thing is performance for me and it is amazing how fast this thing is, considering the possibilities and Java. I am running it on my Linux setup (the only reasonable PHP development OS in my opinion). I suggest it to every developer, least you can do is try the trial. JetBrains also has other similar IDE's for different languages, Python for an example.