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

Erin is a candidate for a warrior from the Fortress faction, but with a rather dubious ability and starting chaos.
Sorgalla also has a not-so-great ability; it would have been better if he had a classic special ability focused on cavalry.
Vaishan and Iranna are generally suitable, but Kifru is distinguished from them by her starting leadership, and her ability at level 3 is also good.

Simply making a warrior from the Fortress faction is nonsense because half of the stats go into spellcasting, and you can't ignore it. Therefore, we can talk about battle mages (or warrior-mages). And in this case, Erin is no worse. The fact that she has chaos is a plus; it gives you a place to put your spellcasting points, and then you can choose skills to your liking for the warrior. Sorgalla has a very useful Battle Frenzy ability for a warrior, and his special ability significantly enhances him (at high levels, the damage from the bite is higher than from a simple attack, if I'm not mistaken).