Just downloaded the demo yesterday.
About Marverni, they have well armored troops, standards, berserkers.
On the side of magic, the druids are not capital-only, are sacred so the upkeep is not high, and they have the Stargazers to act as cheap communion slaves. The Gutuaters make great researchers, being cheap and sacred.
That's my first impressions anyway, haven't had a chance to play much yet.