In your opinion, which faction is the strongest in Heroes 5? Let's discuss the advantages and disadvantages of each faction.

Lethos??? o_O I didn't expect that... since they banned teaching dark spells to your units, he's become useless.
But Veishan, Irana, and Erin are strong. These are the main ones, and personal preference often decides.
And yes, many believe that Dungeon will ultimately be stronger than its opponents.