I used Emacs for 15 years. I've been off of Emacs for about 5-6 years now and I won't ever go back.

Here's why:

1. Refactoring. The refactorings in IntelliJ are amazing. Amazing. The ability to say (yeah, this class is now called Foo instead of Bar) and have everything automatically changed is outstanding. This is a basic example of course but you can also do things like remove a function parameter, and also do things like lookup reverse symbols.

2. Stable. IntelliJ is just amazingly stable. Part of this is that I had to write elisp to get Emacs to do stuff that IntellJ just already provides for me. Everytime Emacs would upgrade I would have to upgrade Emacs.

3. Pair programming. I could NEVER work with other engineers on their code and vice versa. We just didn't speak the same language.

Now mind you I also created a lot of the code you use in Emacs. I co-created EDE for example.