I played Priest with all spells:
Shadow Madness, Holy Nova, Mind Vision, Thought Steal, Mind Control, Light Bomb, SW:P, SW:D, Light of Naaru, Holy Smite, Holy Fire, Mass Dispel, Velen's Chosen, PW:S, Mind Blast.
30 cards.
Most of these cards speak for themselves, but some of them aren't great. Mind Blast and Mass Dispel are relatively weak in this mode, but they're good enough to run because Mind Blast works like a 2 drop, and can help you end the game, and Mass Dispel is situationally great, gives you a 4 drop, and replaces itself in your hand. Light of Naaru is surprisingly strong because it gives you 2 creatures for 1 spell and often lets you trade favourably at the same time, Resurrect is incredibly bad (I tried it and would not again, the quality of your creatures isn't good enough). Divine Spirit seems potentially good, but I haven't tried it yet.
A lot of the Priest spells are really good because they function in a similar way to BGH (remove a creature, gain a creature). Some of the others work pretty well because they're like a Shattered Sun Cleric (buff a creature, gain a creature).
I hadn't thought of Druid, but a mode in which having overpriced spells is actually a good thing is kindof funny.