In which city is the alt upgrade more balanced?

Balance is precisely what you look for when deciding which units to deploy. In this sense, Haven and Dungeon are immediately less appealing, while the upgrades are exceptionally good, especially the 3-headed creatures and the succubi! With Orcs and Necromancers, you can comfortably choose from both, and I find myself particularly torn when deciding between archliches and their healing counterparts! Everything else is a matter of personal preference!