England prized it's North American colonies for many reasons. One was for the valuable natural resources they contained. Virginian tobacco was very popular all over the world, and lumber from New England was quite valuable to create ships for the rapidly growing English navy. Sugar from the Caribbean was necessary to make rum--a staple in English naval and shipping culture. Furs, especially beaver during the early 1800s, were quite important to English fashion. The American colonies would be valuable for their contributions of indigo and rice as well before they became independent.
Another reason that the North American colonies were valuable was that they served as an area where England could send it's potential troublemakers. Maryland, Massachusetts, and Pennsylvania served as lands for religious dissenters--this was important, as religion was considered something to fight over in Europe during this same period. Georgia was a place for what were called the "deserving poor;" it was more humane than a debtor's prison. Finally, Virginia, South Carolina, and the Caribbean were places for ambitious young men to make their money raising cash crops. These young men in turn would hopefully be valuable taxpayers to the English government.