Sansa never cared much for the South. While Sansa may have been a well-suited ruled for the Iron Throne, she ended Game of Thrones in a position she's much better suited for — Queen of the North. Sansa's rule of the North in Game of Thrones will mean that the North is an independent kingdom, although with Bran serving as King of the Seven Kingdoms, she'll likely have a much better working relationship with those in King's Landing than her father ever did.
While all of the rulers in Game of Thrones so far, dating back to Robert Baratheon, have been the ruler of the Seven Kingdoms during their reigns, Bran marks Game of Thrones' first and last ruler of the Six Kingdoms. Sansa's mission has long been to free the North from the rule of those in King's Landing, and there's no easier person to ask such a favor from than one's own psychic brother that doesn't take anything personally. While Jon Snow is heading North to serve in the Night's Watch and explore beyond the wall without the threat of wights and Arya is seeking out whatever lies west of Westeros, Sansa is going back home — a fitting ending for a woman who has changed as much as her home has, and fans were elated to see Sansa finally be rewarded for everything she's been through.
Sansa has been one of the show's most transformative characters, going from a girl who believed her highborn status meant that a good life would be handed to her, to a woman who realized that leaving your fate in the hands of others can leave one abandoned, used, or subjected to truly horrifying acts of cruelty. Sansa began the series as a little bird, and ended it as the mighty wolf that she is.
Sansa's story in Game of Thrones also mirrors the story of Winterfell itself in many ways. Winterfell was once a scrappy, but functional, haven in the North, before its leader was beheaded and the keep itself was sacked by Theon Greyjoy. These two formative moments in Winterfell history coincide with Sansa's own journey, learning that her engagement to Joffrey Baratheon would not be as idyllic or sweet as she may have once imagined. The Bolton's rule of Winterfell coincided with Sansa's imprisonment as Ramsay Bolton's unwilling bride and the time in her life where she was a victim of a truly terrible ordeal. After her escape, however, she used her connections and political acumen to help win Winterfell back from the Boltons and restored Winterfell to its former glory just as she was beginning her rise as a leader.
Sansa grew up hearing that "there must always be a Stark in Winterfell," and while she may not have expected that Stark to be her, it's obvious now that there's no Stark better suited to be in Winterfell than her. The story of Sansa Stark is the story of Winterfell, there is not one without the other.