UD&ORC

If you're playing as Haggeesh, the Centaurs move more often (and if you also speed them up and push them forward...), they can make at least 2 moves before the Necromancer hero casts a spell. And if you split them into 2 squads..., it's true that this isn't effective in a long game (when there are many Cyclops).
The ultimate-level warcry (I don't remember the name) deals damage based on the number (not the quality) of the army, and this can already be useful in battle. (this is also relevant for Centaurs - you can gather quite a few of them).
The main thing to know is that Necromancers almost always play defensively, while Orcs are not suited for this.

I wonder how many Necromancers Igor111 defeated (not against the AI). Any tactic that doesn't prove itself in a battle against a human player has no right to exist. And he's here, boasting about how smart and advanced he is.

Added after 8 minutes
I wonder, Kill, can you tell me how?