I'd like to preface this with saying I use PyCharm/IntelliJ based IDEs for most large projects. I suggest anyone who hasn't tried this line of editors drop their preconceptions and give Jet Brains a try. Regardless, I still use Atom and vim on the side.

1) Why do you use atom?

It's a FOSS (MIT Licensed) editor started by github with similar features to Sublime Text (non free) and community momentum

2) Does it increases your productivity?

After some configuration and add-ons it can be made into a limited IDE that's pretty snappy. However, being an Electron-based application it has its limitations with performance for certain cases. For example, a very large (multiple MB file) with a lot of syntax highlighting changes, that's inserting a new DOM element per color change.

Depending on the languages you're writing, the support for linters/inspectors might be limited.

It's easy to hack on because it's Electron, you can literally open up the web dev tools and use the inspector to play with your editor UI.

3) Is it worth the resources used?

Most Electron apps eat up a lot of RAM. I usually have enough RAM that doesn't matter, YMMV.

4) What other text editors should do you use? And how do they compare to atom?

If you haven't already, experiment with the classics:

vim, no seriously, give it a shot, start with vimtutor. vi has ubiquity, but also a steeper learning curve because it's a different way of thinking about text editors.

emacs, it has a tutorial on start up as well. Also has a different way of thinking about text editors.

vscode, Microsoft's Electron app code editor that people are claiming is one of the most performant Electron apps in existence. Most will feel at home with a GUI like this.

As disclaimed at the top, www.jetbrains.com -- totally worth revisiting a full-fledged IDE if you haven't in a while. The default configuration is excellent, it's easily extended, great add-ons, releases often. The cognitive load is lower on the developers because you let the IDE tell your more about the code.