Some use QtCreator and it's not bad I heard.
I use Eclipse but just as an editor. Compilation and execution is done from command line.
I use Eclipse because I am familiar with it and did not want to learn another IDE.
But I still use QtCreator for editing *.ui files...
Using Eclipse takes quite a bit of setup if you want proper error highlighting, code navigation, refactoring, etc... to work, but it is doable. I even got the debugger to work at some point in time. For GCS only btw.... some have used Eclipse for firmware dev but it's not my case.
Unfortunately, I never got round to make my setup for GCS dev available to others... I still need to externalize a few things that are still hardwired to my particular environment.
PS: I am willing to share my Eclipse setup with whoever want's to take it as is and eventually take it further.