Against which factions is it easier for demons to fight, and against which is it more difficult?

What do you think, are the stats in this game frankly weak, or can skillful play compensate for it, for example, against Dwarves, Haven, or Necropolis?

Skill is needed in any case – for example, playing as Dwarves or Humans against Demons....
As for playing as Demons, the following expression is very appropriate: "Love us when we're dark, and anyone will love us when we're light!" Paraphrasing this, we can come up with the following formulation: "Learn to play as Demons, and you will confidently dominate with other races as well."