WebStorm has both Intellisense-like autocomplete and word completion. Its "Jump to definition" helped me become a better programmer because jumping into library code became a habit - be it Ruby or Javascript (I use RubyMine). They were one of the first editors to fully support JSX, and before that they came first in supporting Angular v1 and its directives. They let you refactor code in dynamic languages, does it silently and safely when the scope is clear, and asks you when not.
When I had to work on a Java project, using IntelliJ was a dream. The same environment, but with sturdier refactoring. Plus it taught me Java idioms by whispering gentle suggestions while programming.
In Rails, when you rename your controller it renames your routes. It has a great debugger integrated that just works. It has support for your rake tasks, at par with the deep integration into all environments it support.
When they changed their subscription model to an yearly fee, I was happy to be giving more money from my limited paycheck to this company. It is the kind of software I'd write love letters to. I make tools for developers, and one day I want them to be of the calibre of JetBrains' products.