Well, they both are to blame that's a fact. Although I do tilt slightly more to the fact that the Britains were the ones who should take the most blame. The British made the colonists land at that time attempted.
You didn't provide any reasons so it's hard to pick a specific answer. However, the reason why the colonists were extremely angry with Great Britain were the imposing of all these unnecessary taxes. There was the Tea Act, the Stamp Act, etc. All of these taxes were what drove the colonists crazy.