Hi!
I made o mod for Heroes VII. Its goal is to give every faction 2 more alternative creatures to choose from (a "strong elite" one and either a "core" or a standard "elite" one). The mod doesn't add any new creatures but selects from the pool of neutral ones. Short list:
Haven: Griffins and Light Elementals
Academy: Shantiri Golems and Air Elementals
Necropolis: Juggernauts and Lilim
Stronghold: Mermaids and Efreeti
Sylvan: White Tigers and Earth Elementals
Dungeon: Shadow Panthers and Darkness Elementals
More details and download here: http://www.heroes7.acidcave.net/ac_mod_eng.html