I understand that you don't think Rhaenyra would have been a good queen, frankly I don't either, but do you think she was the rightful queen?
No, because what I believe about the Dance is that the succession crisis was one of competing and mutually exclusive legal precedents. On the one side was the decision of Jaehaerys I in 92 AC, where he directly flouted Andal-First Men succession tradition (where a daughter comes before an uncle) and declared that his second son Baelon should be the new Prince of Dragonstone. On its face, this decision could be taken to mean that a Targaryen king had the power to name an heir at his discretion - even if that choice went against native Westerosi succession custom. So, case closed, Rhaenyra is the rightful queen?
Well, no. Because there’s also the Great Council of 101 AC, in which a male-line candidate was preferred over a female line candidate (even though that female-line candidate was the grandson of the king’s eldest son, and the male-line candidate only the son of the king’s second son). Nor was this a close race: both Gyldayn and Yandel note that Viserys emerged triumphant by a 20 to one margin. As Yandel then adds, “[i]n the eyes of many, the Great Council of 101 AC thereby established an iron precedent on matters of succession: regardless of seniority, the Iron Throne of Westeros could not pass to a woman, nor through a woman to her male descendants”. Plus, of course, in native Westerosi tradition (save in Dorne, not yet part of the united kingdom), a trueborn son would always come before a trueborn daughter in the same generation.
So, which is it? Is Rhaenyra queen because she was named the heiress by Viserys? Or is Aegon king because he was his father’s eldest trueborn son and the Iron Throne cannot pass to a woman? The answer is that there is no answer, at least not one obvious by precedent. What should have happened, ideally, is a Great Council, which would have settled the knotty legal problem Viserys I never bothered to solve. But, of course, given the extremely selfish personalities of the leaders in the Dance, war became the sure outcome instead.