Paliden and Artificer (I will leave ranger out due to some issues) have a unique space where as a half caster with cool features so they can more or less keep up most times with full casters while not over loading the non casters anywhere near as much.I never play full casters. I know Rangers and Paladins count as part casters, but I put the separation between full and part...
As much as I dislike the new warlock in the playtest as warlock, I think it would make a good wizard. Drop HD down to d6 and remove some prof. Take out the pact cantrip and give them a spell book.