Both Patriots and Loyalists had many different motivations for their positions on whether the Colonies should remain part of Britain or fight for independence.
One issue was religion. Many of the colonists had originally left England in pursuit of freedom of religion. Even though England was becoming more tolerant in practice, in the eighteenth century, not only was the Church of England the established state church, but also there were restrictions on the civil liberties of those who were not members of the Establishment, including inability to hold public office or attend the old universities (Oxford and Cambridge).
Next, a major issue was taxation without representation. Although the Colonies paid taxes to England, they did not vote for Members of Parliament, and thus had no say in how their taxes were used. The colonists felt increasingly exploited by taxes and limitations on economic freedom.
Philosophically, many of the Patriots were opposed to hereditary monarchy and aristocracy, and wanted to establish a republic in which people were elected by universal suffrage on the basis of merit rather than parentage.