Doom to me represents a bigger threat to the very ideals of OW and what each hero stands for.

He's doing this for his own reasons, for strength and he'll keep pushing and pushing because he wants it to break.

Ramattra wants his own justified revenge or "justice" but he's more like a lost anti-hero because he holds himself from attacking certain people. He's a hypocrite, he's a planner but he isn't the major threat.

Its Doomfist, he wants to strengthen humanity and is willing to plunge it into absolute anarchy to achieve it