Which Orc hero do you prefer?

Nah, Keegan isn't a great hero. Or rather, he's not the best hero. Goblins don't offer a significant advantage in battle, and even if you have 200-300 more of them by the endgame, it won't make much of a difference. It's better to choose someone else. Although, theoretically, you could try to level up the "Goblin Cart" skill, and closer to the endgame, use "Protect Us All" (which gives you goblins equal to twice the number of level 3 Orcs). Then their number will be truly huge, the "Wrath of the Horde" ability will deal massive damage, and the chances of magic resistance and trap activation will increase. All that's left is to level all this up, but it's not that difficult. And if you also train heroes to level 6 with a mentor and then use "Protect Us All," giving them all the Orcish warriors beforehand, you'll have thousands of goblin meat! Of course, this is already pushing the boundaries of fantasy, but it's still possible.