Bran is a horrible choice to be king. Ever since he became the 3ER his only response to anything is that it was essentially pre-ordained. The fact that he knows whats going to happen, but doesn't do anything to try and change it makes him useless. He allowed 1000s of King's Landing innocents to die, knowing the whole time that it would end up leading to his being king and Jon being banished.
He will never make an actual decision, because he already knows what's going to happen. Tyrion choosing to nominate him was baffling, given what has actually happened in the show.