well vito did make a drastic mistake by sayin no to the deal, thus causing an entire war, his son gettin killed, his loyal men betrayin him, and micheal turning into the family business. he was still a great don. but micheal never made a mistake in his dealings with the don except for the killing of his brother. he always won in the end. thats why i think mike was the better don. Cuz in that kind of business a compassionate warm hearted man like vito is not wats needed, a cold-hearted and calculated man like micheal is.