A lot of it is just that I worked in Java, Python, Erlang, some Android development, and NodeJS/Meteor so I get to keep all the keyboard shortcuts I have learned without having to switch IDE's (it's basically the same product with different plugins). I had been working the Python/Django for the last few years and it has a lot of features for Django (project creation, built in test runners).
Mostly I like that it just works. I don't need to fiddle with it. The inspections and code-completion are amazing and some of the plug-ins (like the one I use for MarkDown) are great.
But except for being used to it, I am not sure it offers a huge advantage over Atom (the rest of the RC team uses Atom).
I do feel a little bit better knowing my main tool is a commercial product that only makes programming tools, so I am less likely to get screwed by some change in direction later on.