I use two, depending on what I am doing.
The first one is
Visual Studio Community, free as in beer, together with the non-free (but reasonably priced)
VisualGDB add-on.
VS is definitely a powerful and mostly intuitive IDE, VGDB supports a wide variety of MCUs (it's not difficult to add your own, if really needed) and just works for my projects.
The other one is rather an advanced editor with compilation and debug support than a full IDE:
Visual Studio Code.
It is free and Open Source-ish (eh, still Microsoft...), multi platform, able to run in WSL and (still) quite fast, well integrated with git, has lots of handy extensions and developers that listen to the users.
It has replaced Emacs in most of my day-to-day edit tasks, even at work: that's quite a feat for me (sorry RMS)!.
Both IDEs support bare metal AVRs and Arduino: VS via VisualGDB or the non-totally-free "
Visual Micro" extension, and VS Code via the "
Arduino" extension (MIT license).
I sometimes use AVRs, but never Arduino, so I cannot vouch for the quality of these extensions.
Eclipse, I try to keep at a distance. I find it cranky and poorly refined, slow and confusing.
As a cherry on top: I cannot understand how it's possible to have a bodged dark theme in 2018...
But, TBH, I mostly tried some of the vendor supplied Eclipse based IDEs (TrueStudio, MCUxpresso), not the bare-bone Eclipse with the just needed plug-ins.