The most useful unit upgrade.

I think the best upgrades are for the Demonesses and Inquisitors. The Inquisitor is good with a large number of hit points and increased stats. A true tank! And Haven is my favorite faction; it has everything good in it:P

Yes, the Inquisitor's upgrades are VERY noticeable and significant, but are they really necessary? I thought that all humans, especially after the latest patch, were retraining monks into Paladins... you rarely see them now...