Heroes 5.5 WarGame Edition - Tactical Edition.

Why is there such an imbalance in the starting armies? Some have a much stronger army than others.

Where exactly? Check the prices of the creatures in the first posts of the topic (on the first page). The total value of the army is about 2,500 gold. Minus the wagon (0.5), tent (1.0), or ballista (1.5), if they are available.