> It's a bit of an investment if you're still a student
They have free licenses for students that includes all their products and a discount when you graduate. If you're making money off it, the license cost for intellij or just webstorm is pretty cheap.
Beyond the basic functionality working, the paid versions have a lot of cross-langauge support (PyCharm gets a huge chunk of the JetStorm functionality) which means that autocomplete "just works".
Like when I'm writing Angular templates, it looks up my custom directives and provides autocomplete on that. It is able to give autocomplete inside Angular expressions (down to looking up the controller and providing type information if you're using Typescript) inside my Django templates.
It's a lot of fuzzy searching but they have very good heuristics.
I think it would be near-impossible to get this cross-language support in Atom/Emacs, if only because it requires the I in IDE. Totally worth it.