2Erganor
Is this based on experience playing against the AI?
HAVEN: Ellaine as the main hero? Never, only as a support hero in the castle. Never as a starting hero either. But you're wrong to forget about Myv; she's a beast for many endgame scenarios.
SYLVAN: Dirael is a very viable hero, as is Ossir. Wingael has been nerfed, but is still strong.
DUNGEON: You forgot about Leto, Leto. It's no coincidence that he's currently leading in tests for the fastest leveling speed among all dark-skinned heroes. Vaishan and Sinithar are also worthy choices. Many have suddenly abandoned Erin and Iranna.
ACADEMY: The champion there is Hafiz. Nur and Or. Nazir is a solid mid-tier hero, although sometimes very strong.
NECROPOLIS: Kaspar, Zoltan (easily gets the "Mark" and extra knowledge). You can level up Deidre on large maps, but not as a starting hero.

Ellaine as a starting hero is actually quite good, especially on large maps. In such cases, you'll likely find another "native" hero in the tavern, and near the castle – free peasants. Ellaine is used for hiring troops because she has the "Recruit Troops" ability, as well as supply and other abilities. And the second hero, hired in the tavern, does the fighting. Regarding Leto, you need to consider the skill slot spent on dark magic, and also his complete uselessness in fighting undead, which are immune to his professional ability. As for Erin and Iranna, they were wrong to give them up, very wrong... But regarding Hafiz, unfortunately, I admit I was wrong! If properly developed, he tears through almost everyone. You just need to create appropriate minor artifacts for mages.

Added after 4 minutes
Regarding Deidre: First, there's an error in the hero's description. In reality, her profile is improving the effect of the Banshee's scream as she levels up. She's a kind of anti-Godric. Second, she can be a starting hero. But I agree, only on large maps.