Elves - I already mentioned... it's strange that their city is in the water. Too much water is harmful to wood.
Mages - a cool, floating city.
Demons - a tower. It was better in the 3rd game, although it's difficult to make it the same in 3D.
The Hammers of Fate - I don't like it; it's not clear where everything is located.
Necropolis - nothing special. Tall spires... it would be better on a hill.
Fortress - ..., I like it more when they live in the mountains, not in a pit. Hehe.
Stronghold - good. Better than the previous four. Although a desert would look better.
IMHO.