You'll love KDE. It has always been one of my favorites. Plus the close integration with Qt makes it even better.
I've used gnome a lot lately too though. A lot of people hated the new Gnome 3 changes, but I didn't mind them.
It's not as full featured or nice as KDE though. But sometimes KDE acts a little weird due to some of the opengl stuff.
And if all else fails, you can try arch. It isn't an easy to set up distribution but it's cutting edge. So everything is the newest of the new. Makes for a lot cooler of a linux experience in my opinion. :)
Setup is not for the faint of heart though. There's no GUI, and I usually use a linux boot disk to get it going (one from sysreccd).
Linux mint, being based on Ubuntu also shares the same packages (I use Kubuntu). QtCreator is a separate package and doesn't actually install any of the development packages needed as far as I know (it just recommends them). Do sudo apt install qtbase5-dev qt5-default qtdeclarative5-dev, you won't be able to see the kit right away, go to Tools -> Options -> Build & Run -> Qt Versions -> Add Kit add /usr/bin/qmake which should link to qmake qt5. A list of Qt5 dev packages and their respective modules.
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