I think that in assessing the factors that drove the calls for independence one has to weigh out the importance of economic rights and political rights. For the colonists, the need to be free on economic ground and political grounds converged. It becomes a challenge to parse out which one played a larger role in their minds, driving them to the embrace the calls for independence. It is for this reason that historians have to end up assessing with their own criteria which ones played a larger role in advancement. For example, the colonists' desire to make and keep their own money might have driven them to call for independence with so much in way of British taxes and acts on the Colonists. For example, the passage of the Quartering Act and the Stamp Act ended up taking an economic toll on the Colonists. Both acts took away some of the colonists' right to keep and make their own money. Yet at the same time, these acts could be seen as fundamentally wrong to the colonists' sense of political rights, as both acts took away from the colonists' ability to live a life free from intrusion. The Quartering Act's insistence that individuals surrender their homes to British troops and the Stamp Act's drive to control the media and thoughts of the Colonists could be seen as acts that violate the sensibilities of the colonists. In assessing acts like these, the historian has to assess both on the level of importance to economic and political rights to the colonists.
The biggest political factor was the French and Indian War. The war was decided by the King and Parliament with no representatives from the colonies. Yet, the colonists fought and died in the war for Britain. After it was all said and done, the war was financed through a lot of taxes on the colonies. Thus, the term "taxation without representation was coined." The colonists were being taxed for a war that they never had a say in.
Economically, you could say, this falls under the very simple inverse relationship between price and quantity demanded (Qd). When the price (taxes in this case) for the good is lower Qd is higher and vice versa. This is because there is a smaller opportunity cost ($1 you pay in taxes is fries at McDonald's you can't have) for a lower price and a greater one at a higher price. For the colonist, their price (taxes) skyrocketed and therefore their quantity demanded (their desire to be a colony) greatly declined.