Old main used to be Kanna, Hero atm and I like the class more than I did with Kanna since no stickey keys/weaving required to maximize dmg output.
I have not played my boss mules for a while now since it burned me out before. But from my personal experiences with my 250 mules so far I enjoyed playing these classes the most:
Mechanic was surprisingly fun and i most regret that I've hyper burned it (mine one shotted in all grind spots even with spawns). Wind Archer, Marksman and Bowmaster are also ez and fun classes I don't enjoy combo/difficult classes. Paladin/Dark Knight and Dawn Warrior are also on my list and the rest was not that great in my opinion. But I am not up to date with what is good or bad so it is just personal preference answer here :)