Neutrals:
Medivh is exciting and strong, especially in Yogg lists. Expensive though. Won't make many lists, but the ones it does will be a load of fun. Can it make Hunter is the biggest question. I could see this in a Renolock deck. Works nicely with a lot of their big spells. It probably doesn't make Yogg Druid, Arcane Giant might see play in that deck.
The Curator: I like this card but reminds me too much of Mysterious Challenger. This card is very flexible and could see a lot of play. The Taunt and specific-3-card draw are both strong attributes.
Malchezaar is a fatigue list dream and can fit in Reno and some other control lists. Won't make fast/aggro decks but should see a lot of play elsewhere.
Barnes is an OTK dream, N'Zoth dream, and lots of janky shit dream. This card will be fun.
Moroes works in token decks. Druid/Paladin most likely but even Zoo could play him. Zoo lacks the buffs to keep him around very long.
Arcane Giant should slot into Yogg druid very easily and even Yogg Hunter or any Yogg list tbh.
Book Wyrm: Trash. Blackwing Corrupter so much better.
Moat Lurker seems like a really fun card that opens up so much possibility. Definitely going to try fitting him into a variety of lists. Can use on your own minions to "revive" them later, or use on enemy minion to temporarily remove a huge threat. Combos well with Purify
Avian Watcher works great in a Reno Mage... Niche usage. Doubt it would even see play in Wild.
Menagerie Magician maybe opens up some sort of new zoo deck, could be good, or very annoying. If it works it's not going to be enjoyable to play against. 5 mana and very conditional makes it expensive and not consistent. Niche card.
Arcanosmith could be another enabler for Divine Spirit Priest. 4 mana 3/7 stats is not bad. Also could work in Bolster warrior. Not sure if it sees much play, could be a sleeper.
Violet Illusionist works nicely in Warlock but also allows Rogue to do some clearing with her face. Doubt it sees play elsewhere.
Zoobot same as Menagerie Magician, but cheaper, less of a buff. Inconsistent but stats are ok. Better than Magician imo. Niche.
Pantry Spider seems bad but 3 mana for 2/6 stats might work. Grub is 3 mana for 2/5 stats but depends if you value 1 minion more than 2. This card means you have a more guaranteed Houndmaster as it's unlikely both get cleared before your next turn. Usually better to have more minions so arguably better than Grub.
Nethersprite Historian obviously fits in Dragon decks. Only dragon deck in meta is Warrior but with the new 3-drop maybe Paladin comes into play.
Pompous Thespian power creeps Frostwolf Grunt. Has too little health for the taunt to be worth it. Unplayable.
Arcane Anomaly probably unplayable. With coin+secret it can be a 2/3 on 1 mana in secret paladin, but secretkeeper better anyway. Shaman Maelstrom can get this.
Runic Egg unplayable, but can be summoned with Maelstrom. More card draw for aggro shaman.