Which hero is the best in the Tribes of the East expansion?

Irabeth's ability might be useful in a game against demons, but overall, it's essentially a weaker version of Leto. However, Kifrah is a good hero, albeit a specific one: she's practically the only candidate for leveling up a warrior-type hero with the "Tactical Expertise" skill, and she can also be used effectively against engineers.

I mainly play with Synitar, but recently I've also started enjoying Leto (a combination of plague and invisibility).