hi, i will five my personal answer here.
Please, facts apart, consider it as my own opinion taken from my experience.
atom and the advanced editors
simple editors like pluma or geany are not enough forntrue development, but advanced ones, like atom, are very very powerful and extensible, they can refactor code, run linters, provide intellisense completion, and they want to be a unique small tool to rule all the languages at once.
please give atom a try if you want to take this path.
IDEs
IDEs are more language-centric, and they don’t pretend to be the killer application for every language, but they tend to do one thing and do it well in a classical but complete approach.
the jerbrains world
jetbrains products are open source and released under the MIT license, and they release precompiled binaries for intellij idea (mainly java) and pycharm community (mainly python) for free.
additionally jetbrains releases more advanced versions of both idea and pycharm, plus other specific IDEs for c/cpp (clion), ruby (rubymine), php (phpstorm), web languages (webstorm) and some others.
these additional tools are based on the open source intellij core but include some additional proprietary plugins to blend them into different products.
the free editions of intellij and pycharm can be extended via free plugins to support additional languages for free, and they are not limited to java and python.
they also offer free licenses for open source developers, in facr all the parrot developers have access to a free jetbrains license that unlocks ALL their products.
p.s.
you can review the source code of all the jetbrains products (including paid ones iirc) on their github profile.
netbeans
netbeans is an awesome IDE for java and its previous version developed by oracle was really really powerful, but suffered the limit of being shaped around java 8, which is now EOL (end of life) and no longer available on many modern rolling release distributions (including parrot).
the future of netbeans is very promising, in fact it was dropped by oracle and adopted by the apache foundation, and the new apache netbeans 9 release removes the java 8 limit.
i tried it for 30 minutes and i saw a severe lack of plugins and language support for this new release, and i don’t know if it was my error or if the project is still migrating the old plugins to the new version.
i was unable tp install a dark theme and python support, but as i said, it was just a 30min test
qtcreator
the best, more lightweight, more powerful, more portable, more awesome, more more, and more everything environment i have ever worked with!!!1!!!one!!
unfortunately it only supports c, cpp, qt dialects and qml, then no python, ruby, java or php support.