First I would ask if you are looking to play a tank, healer, or dps? If you're looking for least amount of pressure or responsibility then you'd want to go DPS or otherwise called DD for damage dealer. If thats the case, Archer or Thaumaturge would be the easiest ones to pick up. If you don't mind being a leader and having the pressure of being a tank, Gladiator is a rather simple class to play as far as button pushes and combos. But there are always exceptions and in order for me to give a best possible suggestion, I would need to know what exactly you are trying to achieve in your game.