At the start of the New World, Jinbe primed us for the two big villains besides Imu
The rise of those two were the two chief changes in the world.
But which of the two will go down first?
Blackbeard?
He hasn't defeated Shanks yet, which should happen before he loses to Luffy. He wasn't impressive against Law. Still time to grow for him. Luffy will take him on when he is on his zentih.
Therefore, I go with Akainu.
Just look at Luffy's reaction. His scar throbs, when he thinks about Sakazuki. Just as Shanks' scar aches when he thinks about Teach.
I believe Blackbeard defeats Redhair aroudn the same time Luffy defeats Reddog

The rise of those two were the two chief changes in the world.
But which of the two will go down first?
Blackbeard?

He hasn't defeated Shanks yet, which should happen before he loses to Luffy. He wasn't impressive against Law. Still time to grow for him. Luffy will take him on when he is on his zentih.
Therefore, I go with Akainu.

Just look at Luffy's reaction. His scar throbs, when he thinks about Sakazuki. Just as Shanks' scar aches when he thinks about Teach.

I believe Blackbeard defeats Redhair aroudn the same time Luffy defeats Reddog