Which faction is the most interesting to play as, and what strategy do you find most engaging?

in general, I think you should play either as Demons, focusing on opening portals, or as Orcs, as they are strong if you have a good army and the "Wrath of the Horde" ability. Elves have good racial abilities. For the Undead, you can quickly build up your army. For Dwarves, you need to be good at using runes. For Mages, you have many archers and strong, large creatures. And for Dark Elves, if you take Assassins and Shadow Lords (level 2 upgrade) and upgrade all the others to level 3, you'll have a strong army. In general, when building an army, you need to choose the highest possible upgrade level.