Which revolution- the American, British, or French- contributed most to the development of democracy?
The answer to this question is, of course, largely a matter of personal opinion. My own view is that the English Revolution contributed the most to the development of democracy. This answer assumes that the English Revolution referred to in the question is the event also called the Glorious Revolution.
I would argue that the English Revolution contributed the most to the development of democracy in part because it was the first of the revolutions. We can argue that it came first and helped to inspire the other revolutions. This makes it more important.
More importantly, I would argue that the English Revolution made the American Revolution possible. The English Revolution created a constitutional monarchy in the United Kingdom. This made it possible for people in England to talk of the “rights of Englishmen.” It gave the English the idea that they had the right to self-government of a significant nature. If English people had not felt that they had this right, the American colonists would not have been so eager to demand self-government for themselves.
Finally, my view is that the English Revolution was a more important advertisement, if you will, for democracy. England at the time of its revolution was a much more important country in the world than America was when it gained independence. The creation of a fairly democratic system in one of the strongest and richest countries in the world was more important than the creation of a democracy in an upstart country like the United States. Furthermore, the English Revolution was accomplished without the atrocities that accompanied the French Revolution. This means that it made democracy look like much more of a good thing than the French Revolution did.
For these reasons, I believe that the English Revolution contributed more to the development of democracy than the other revolutions did.