I don’t mean this to be an “easy-out,” but I think ultimately the answer to the poll is the Catholics and Orthodox.
In the case of both the Catholic/Orthodox and Catholic/Protestant rifts, I think that if everyone could take a mental time machine and consider the state of the Church at each time we might be able to reconcile our problems.
The Orthodox have a stronger claim than the Protestants and I don’t mean that to be inflammatory to the Protestants. I just feel that the Church had problems at the time and a few very charismatic individuals got a little overzealous. For that matter, Hilaire Belloc would even argue that Luther himself would be horrified to learn what had developed. Reformation was necessary, yes, but I think what we got instead was a Revolution.
I think there are answers and reconciliation possible, but the compromise will have to be heavy in the case of the Protestants and possibly to a lesser extent with the Orthodox (though I freely admit I don’t know much of their position).