Your favorite hero...

Excluding the overpowered heroes from the campaigns, it's roughly like this:

Inferno - Nimue
Dungeon - Erin
Sylvan - Dyraelle
Stronghold - Haggeesh
Haven - Axel
Fortress - Helmar
Academy - Ora
Necropolis - Lucretia

While not all of them are the absolute best or most overpowered, I don't always aim to choose those.