It just so happens that I also like Chaos and Nature the most here. These two factions move around the map very quickly (relatively speaking). The others don't, especially Might. Well, and everyone has decent units, and there are no bad spells...
Why especially Might? O_o
Birds run fast with heroes :) So they have a normal speed, both at the start and during the game.

Барон "Vampires"
Отдай свои прошлые сны,
В сомненьях себя обрети,
В бешеном танце душа кружится!
Не думай, что будет потом,
Здесь и сейчас мы живем,
Стань хоть на миг сам собой, слышишь!