In terms of the geography and climate, the middle colonies provides plentiful amounts of food. There are wide rivers, bays and harbors and the climate is just right. The winters and summers are mild and the temperature slightly varies as you move farther north or south. The land near the coastline is flat and slowly rolls west into the Appalachian Mountains. The mountains could be a slight problem as they might get in the way, but not a threat to a victory.
In terms of economics, the middle colonies are successfully supported by
trade of numerous, continuously growing staple crops. We also produce textiles, have lots of timber, and we have accessible iron which would be very beneficial. The political structure includes a provincial council with 18-72 involved which would be an extra help in war although these men might not be as loyal to the king as other men.
The middle colonies are very culturally diverse as we are known for religious freedom. Different religions means different beliefs, Quakers would refuse to go to battle as war is against their religion, they are pacifists, another challenge. All of these different ethnicities and backgrounds cause challenges with loyalty to the king, englishmen are more likely to support the king's orders.
Most colonists are still loyal to the king and would fight for him. He gave them the privilege to go to the new world.