I wonder about this a lot. Is Jacob more powerful then MIB, or is MIB more powerful then Jacob, or are they equals? I think you can argue for all 3 arguments. I'll put down what I know and believe
Pro Jacob Argument: He has been able to keep MIB from escaping the island. He has been able to bring people to the island. He's been worshiped by the people of the island. Is able to make people live forever.
Equal Argument: They both can't kill each other directly. They always communicate to each other as equals. They both have created an army to represent them (poor wording, but hopefully you know what I meant). They both seem to fight over people equally to join there side, with neither of them winning out usually more than the other.
Pro MIB Argument: He can become the smoke monster and kill anyone he wants on the island (except Jacob). He was able to indirectly kill Jacob. Apparently if he is able to escape, the world would be in danger. He is able to transform himself into other people. Apparently Jacob can be replaced, however, we have never heard of MIB being able to be replaced.
I know there are plenty more arguments for all 3 of them and that I am just putting the brief versions of each. But thats why I want to see where everyone else stands on this and perhaps you can add more reasons to back up your argument.
Lastly, not directly related, but still related. Why do you think Jacob wants to prove the MIB wrong? Would that stop him from trying to escape?