I think that the haki that whitebeard has is the protect his sons. Some chapter before I think sengoku wants ace to become the pirate king. And isn't what white beard doing now is trying to guide the youth to their own future. I mean his the current king of the sea he can just use his authority to seek every island in the new world to find one piece. But he didn't. So I think its safe to say that luffy has higher ambition than anyone their. His ambition is to become a pirate king to begin with
But if its against black beard which is has the same ambition as him. Maybe they have the same haki.
btw if hancock has the same haki as luffy but what's the main ambition of hancock? did she also want to become the pirate king? or she just has a high status.