Bran Truly Was The Best Possible Choice To Rule
For many years, near-endless debates have been had about (1) who would be the best ruler (in theory, out of all possible candidates), and (2) who would be the actual ruler (or "winner") in the end.
Turns out both questions have the same answer, I think: Bran Stark.
Incredibly wise and knowledgeable, consummate good (I can't recall ever seeing or reading even the faintest hint of darkness or badness in him; he was always clearly one of the most "pure good" characters in the story), and
He doesn't mean that Bran is a great story teller. Tyrion means that Bran's journey of hardship from broken boy to seer was the most convincing one of all the possible candidates. He was the rightful Lord of Winterfell as Ned Stark's eldest surviving son, and yet he never sought that position. You'll recognize that Bran's story was that of the Last Hero from Old Nan's tales. His was always going to be a story for all the ages. That makes a great story because it will be so long remembered. It's