Of all the main characters still standing on HBO's Game of Thrones, Maisie Williams' Arya Stark has by far had one of the most impressive journeys. When the series began, Arya was scarcely ten years old, a trouble-making little tomboy who dreamed of fighting with swords and detested all things ladylike. Over the years, she's learned swordsmanship from the first sword of Braavos Syrio Forel; trained with professional assassin Jaqen H'Ghar; forged an unlikely bond with Sandor Clegane; fallen in love with a Baratheon bastard in Gendry Waters; and fought tooth and nail to get justice for the wrongs that have been done to her family.
All throughout her journey, Arya has consistently shown herself to be capable of the kind of leadership that not only the North but all of Westeros so desperately needs. Leadership may never have been one of Arya's goals, but it's become quite clear that she's one of the best chances Westeros has at having a truly capable, benevolent leader. And at the very least, she would be so much better than either Jon Snow or Daenerys Targaryen could ever be. Here's why, with spoilers for everything up until season 8, episode 3.
Better Than Daenerys: She's capable of rationality without a team of advisors
Over the course of the series, Daenerys Targaryen has had so many advisors, it's almost hard to keep track of them all: Viserys Targaryen, Ser Jorah Mormont, Missandei, Ser Barristan Selmy, Daario Naharis, Tyrion Lannister, Varys, Ser Davos Seaworth, and the list goes on and on. All of these people have shaped her to become the leader she is today - for better, and for worse. And all the while, she has been incapable of leading on her own without some form of guidance.
While Arya has never been in any sort of position of leadership with the level of responsibility Daenerys is forced to bear, there's no denying the fact that she's always been capable of independent thought and independent action. She doesn't need to be told what to think, or say, or do. She simply thinks, and says, and does - and usually, she's right.
Better Than Jon: She doesn't shirk her duties
"The man who passes the sentence should swing the sword." One of the central tenets of House Stark is the belief in honor, in fidelity, and in owning up to one's responsibilities by extension. Jon has had moments of honor throughout the series where he's kept to his word and performed duties as they've been expected of him. But on more than one occasion, he's been petulant, complained of what is expected of him, or outright rejected it altogether - even walking away from the Night's Watch despite his lifelong pledge.
Arya has made no such pledges in her life, but her honor cannot be doubted. She is always true to her word and always exacts the punishments and takes up the duties required of her. She embodies not only the knowledge of Valar morghulis, but also Valar dohaeris. She knows that all men must serve - and so, she does.
Better Than Daenerys: She's lived a more fully-rounded life
Daenerys Targaryen has lived a relatively privileged life. Even if her family was deposed from the Iron Throne through the murder of Mad King Aerys Targaryen, and though she has certainly been roughed up on multiple occasions, it's still true. She has spent almost the entire run of the series in positions of power, wealth, and luxury, and she's always been able to get her way in the end - no matter who she has to burn alive to do so.
By contrast, Arya Stark has had one of the most fully-rounded lives, packed with disparate experiences, of the entire cast. She began the series as the privileged daughter of the warden of the North, who became Hand of the King. After that, she roamed with raiders and the Brotherhood without Banners; served the Many-Faced God in Braavos as a briefly blind servant; fought to survive in the wild all on her own; and became a true tactical genius along the way.
Better Than Jon: She's out-manipulated manipulators that have made a fool of Jon
"You know nothing, Jon Snow." Far and away one of the most famous lines from the entirety of Game of Thrones, what once began as a bit of flirtation between Jon and his lady love Ygritte has been proven right time and again. Jon Snow has almost routinely been made to look a fool by various people, including the men of the Night's Watch; Petyr Baelish; his Northern bannermen; Melisandre; Sansa Stark; and more.
He's also been unceremoniously upstaged in that regard by Arya herself. Arya has gone toe-to-toe with the likes of Melisandre and Sansa over the years, almost always emerging victorious from any war of words that may ensue. And it was Arya who got the last laugh in her encounters with Littlefinger, as she executed the master manipulator who sowed some of the first seeds of dissension within the Stark family.
Better Than Daenerys: She's trained to defend her people herself
In the Battle of Winterfell, Daenerys finally got her hands dirty herself as a last resort, when she engaged - messily - in combat with Ser Jorah Mormont, protecting her and taking blows for her each and every step of the way. Beyond that, however, Dany has largely relied on the use of her dragons as her weaponry over the years.
Leaders don't always have to get involved in handling fights themselves. But you can't deny that it's much more effective to know that your leader would fight tooth and nail for you on the battlefield, rather than circle around in the sky on the back of their dragon while you were risking your life to protect them and your people. Arya is one of the most skilled fighters and killers in the entire series. Daenerys could never hope to compare.
Better Than Jon: She knows the in and outs of King's Landing and the Lannister world
In a way, Jon Snow has had one of the most isolated storylines in the entire series. For the first five seasons and then some, Jon resided at the Wall and beyond, with little to no communication with regular society. After returning to take back the North, he briefly journeyed to Dragonstone before once again retreating to Winterfell. The extent of his journey throughout Westeros has been shockingly limited.
By contrast, Arya has traversed the Seven Kingdoms much more freely - including some of its most important locales. In the first few seasons of Game of Thrones, Arya got to know the ins and outs of the politically treacherous world of King's Landing - and, in particular, the ugliness of the Lannister clan. She knows how their minds work, and how the seedy world of King's Landing works, far better than Jon does.
Better Than Daenerys: She believes in justice over vengeance
"Burn them all." That was the mantra that the Mad King Aerys Targaryen recited over and over again, leading up to his death at the hands of Jaime Lannister. Aerys was driven by madness and the need for blood and spur-of-the-moment petty vengeance. And in many ways, Daenerys has been driven by the exact same things, even once uttering the infamous "Burn them all" line herself.
While you could argue that Arya has been driven by her need to avenge her family's heartache, it's also clear that Arya's quest for revenge is not the same kind of petty vengeance Daenerys exacts. Arya is driven by justice, by balance, and by the greater good. Daenerys doesn't know what those are.
Better Than Jon: She's fiercely loyal to her people and won't compromise their loyalty
In the penultimate episode of season seven, Jon Snow did the unthinkable to House Stark loyalists and Northern supporters everywhere: he (metaphorically) bent the knee to the foreign-born Dragon Queen, and thus surrendered his role as King in the North - and Northern sovereignty along with it. When he returned with Daenerys to Winterfell in the eighth season premiere, he was rightly critiqued by his previously fiercely loyal Northern supporters.
If there's someone who would never disappoint the North, it's Arya Stark. Everything Arya has done so far in her journey has been in support of House Stark and of the Northern regions by extension. She would never turn her back on the place that made her who she is - even if Jon has already done exactly that.
Better Than Daenerys: She's not entitled
One of the biggest problems people tend to have with Daenerys Targaryen - both within the series and within its incredibly passionate and vocal fandom - is her air of arrogance. Practically from day one, Daenerys has felt entitled to the Iron Throne, regardless of the fact that her father was a mass-murdering tyrant and that she herself shares many of the same traits. Friction has especially arisen in recent episodes, when it's become abundantly clear that Daenerys cares more about power than ruling well.
Arya, by contrast, would never have such a problem. She has never felt entitled to power in any way, and has worked harder than almost anyone else in the series to arrive at the point where she is today. She would be a truly committed leader who would never once take the privilege of her position for granted, unlike the Dragon Queen herself.
Better Than Jon: She ended the Long Night
If you ever asked any fan of Game of Thrones who it would be to kill the Night King in the end, it would have been easy to expect them to say Jon Snow. Jon Snow was expected to be Azor Ahai, the Prince Who Was Promised, the savior of the realms. He was meant to bring an end to the Long Night before it ever even truly began.
But as the Battle of Winterfell showed, Jon was none of those things. He was almost entirely useless in one of the most important battles in the history of Westeros. And who saved the day, and very well might be Azor Ahai herself? None other than the Night King slayer Arya Stark.