Which faction poses the greatest challenge for the Dwarves?

Well, I actually know quite well what Gnomes are capable of in late game, and you, Erebus, don't need to teach me. I even played with Mishgan. And if you're interested, you can ask him what Necromancers are capable of in late game. And you just keep changing your mind, praising one faction and then another. Is it just youthful maximalism?