The only thing I would like to add is that heroes of the same faction should have different development paths (2 or maybe 3) - a difference in the probability of skill and attribute drops, so that you can choose a hero depending on the development strategy (a greater emphasis on magic or combat characteristics; defense or attack, for example).
In Heroes of Might and Magic III, it's roughly the same:), with a development focus in three directions (mage, warrior, and battle mage).
