Ideal is hard to quantify here, but if we focus on maximizing representation and effectiveness at the same time, then it's fair to say that these forms of government were uniquely successful. Despite their flaws and failures, they still seem to be the best at maximizing those two variables. Prior to the U.S., people accepted Plato's sensibility that all forms of democracy devolve into authoritarianism -- which obviously is a meme that persists today. (It's worth pointing out that at the same time the U.S. was forming, France had its democratic revolution which ultimately settled into Napoleonic rule.)
The racism of the Enlightenment authors I mentioned is fairly staggering. It's hard to reconcile that with their work, even at the time it was written. Despite that, America now has 100% suffrage and managed to retain its government structure (via a civil war).
Great point; I agree that I shouldn't have used the word "ideal", because it's not at all ideal. Constitutional democracy sucks; it's just much better than any alternative. (I think Churchill said that.)
He said something like that, but he didn't say he originated the thought. In the house of Commons, he once said:
"...Indeed it has been said that democracy is the worst form of Government except for all those other forms that have been tried from time to time."