I'm looking for the closest thing I can get to Civilization in a fantasy milieu. I've tried several games, and Fallen Enchantress and Warlock: Master of the Arcane both come reasonably close. Warlock is a little cartoony, though. I just bought Heroes of Might & Magic V from GOG, and it doesn't seem to be anything like what I want. Are there any other titles I should be looking at?

The best ever was a game called Master of Magic. It's from the 90's, and available on Good Old Games.

I'm pretty sure someone's made a mod or ten for Civilization that would fit in that category....

Here

What about any of the Age of Wonders games?

The vanilla games a so-so, but AoWII: Shadow Magic is awesome, due to a very good community patch and an active modding scene having evolved around it.

I personally loved the hell out of the original AoW. AoW2: Shadow Magic was also strong.