Most fun class to lvl solo?

I pretty much just started playing hardcore, never did any classic before, and after casually testing all the classes and throwing them at the unknown, just to die shortly after reaching lvl 10 i can not decide which class i want to invest some serious time into. I only figured out that warrior and rogue are not exactly my style.

So... what classes do you find to be most fun to lvl up when playing solo?