What leaders and minis would you like to see added to the game?

I don't know much about WoW lore, but seeing familiar characters from Hearthstone and Heroes of the Storm pique my interest in their potential inclusion in Warcraft Rumble. Of course, the game's lore is very rich and extensive, so it would be difficult to include all the cool and important characters so quickly.

Considering the families and their minis currently, who are your favorite candidates to initially join the game? I'm personally excited by the idea of the Lich King as a raid boss and obtainable leader like Ragnaros. I also thought that maybe Deathwing could be the next final boss if PVE gets expanded. But what do you guys think, what other families and dual faction leaders would be cool to see in the game?