Initially I adopted Eclipse instead of Emacs because it was more powerful to search code, and it allowed refactoring. I regularly tried other IDEs but always end up back to Eclipse, even though there has been less big improvements in Eclipse in the past years (but lots of small ones).
I just saw today that Eclipse allowed programmatic refactoring. Now that's something quite amazing, and I don't think other IDEs do that yet. Someone even had fun writing an Eclipse extension in Scala to add a particular kind of refactoring to Eclipse.