Luke Skywalker has been stated by George Lucas, to become the most powerful Jedi to have ever lived. And its been stated in multiple books that he is of the greatest duelists to have ever lived. And Sidious topped him in a duel(Not a Force Duel but a lightsaber duel) and Mace topped Sidious in a duel. (Remember, Lightsaber Duel, not Force Duel).
And Prequel Jedi Order is the greatest Jedi Order in terms of power, thats G-Canon.
To add to this, what that means is that Jedi Order has had pretty much had almost all the time to perfect and hone their skills and become stronger over time because there was no war up until that point that would cause many jedi to die. Therefore, that particular Jedi Order would have great jedi then the rest that got killed in the various wars because they died or some other reason.