I say essence, because its versatility, but it requires a player that know how to use it wisely and perfectly, going by brute force is not good really, but if you know the exact spell at the exact momment, essence is simply incredible and very enjoyable to play.
Ok, here we go...
I'd pick Arcane.
Of course! If essence have had a healing list, that would be my choice, no doubt. As essence does not have one, I guess arcane has the greatest variety of spells and possibilities. Then again, one may do a lot with talents, skills, TPs etc. I've no doubt played the magician the most - thump wizzards indeed
For that, if you allow talents, do the same than me, select the "arcane" talent and learn "arcane healing", I selected it at level 0 so I selected "arcane healing" as one of my base lists (as you can select up to 4 in open or closed lists as base). I see no problem as arcane is really a mix of the three realms, then spell users can learn some arcane lists with talents, as you have enough knowledge of arcane (1/3) to do that IMO.