Depends of many things. The game have e lot of randomly issues.
Also depends what game u play - a short one or a longest one.
I don`t think there are human player who know all of the game and how it work.
I can say there are some heroes, which have overpowered speciality. And some of them have a over overpowered unbalanced.
One of the major speciality, maybe the most op of all is logistic, there are few heroes which have logistic, but Dessa logistic is op than another.
Same example with Crack Hack - he is not the only who have offence as speciality, but nobody rise up attack like Crag Hack.
The same is with Tazar - armored like no else other.
Also in example if u play a longest game or with/agains bigger armies, there are one hero with unique speciality - Loynis with Prayer.
Also there are Sir Mullich wich special ability is very, very overpowered.
There also have a differences between mage and mage, and warrior and warrior, some warriors or mages rise up their parameters balanced, but another not. Attack, Deffence, Power and Knowledge i mean.
Atm i like to play with Tyris, it is very rare to got unuseful skill.