Here's one more vote for QtCreator + CMake.
I've been using it on my project and it's pretty nice, and easy to learn too. I actually had problems using Qmake (.pro) files, and have had no problems whatsoever since the switch to CMake. It also makes it pretty easy to divide your project into submodules/libraries that it will almost automatically link to your final binary.
Using CMake has lots of advantages too, like:
- generate project files for major IDEs
- configure system to enable/disable features at build time
- easy to configure the builds for each OS
- lots of documentation online
- really fast
- detects modified files and only recompiles what's needed
And probably a lot more I can't remember right now.