I tested many classes to know how easily they do quests and grind. Two of them really caught my attention.
First one is Blighter, obviously. Since it has a good damage output and also a good defense. Capable of fast killing and also surviving more 2 or 3 mobs at a time.
Second one is Sorcery, Witchcraft classes like Daggerspell, Demonologist, Arcanist. They also have an incredible damage output while having the Enervate/Grip combo for healing while fighting.