It's incredible how often Sansa's canonical classism/sexism gets ignored by fandom at large when it's a HUGE part of her character.
Yes, all the main characters in the series are classist to various degrees because they are all part of the nobility in a feudal setting. However, with Sansa, it's actually baked into her characterization and defines her relationships. It's one of the reasons for why she and her little sister don't get along and why she rarely shows up in Jon's memories of his siblings in Winterfell and vice versa.
I see posts about how much Sansa would have loved Ser Duncan the Tall because he was the perfect knight and it makes no sense considering Ser Duncan was born in fleabottom and part of the smallfolk that Sansa doesn't care for or understand.
Duncan is not of the nobility and that MATTERS to Sansa as much as her stans headcanon it away as not being important because it does not fit into their romanticized, idealized version of white femininity and the perfect Disney princess.
Sansa knew all about the sorts of people Arya liked to talk to: squires and grooms and serving girls, old men and naked children, rough-spoken freeriders of uncertain birth. Arya would make friends with anybody. This Mycah was the worst; a butcher’s boy, thirteen and wild, he slept in the meat wagon and smelled of the slaughtering block. Just the sight of him was enough to make Sansa feel sick, but Arya seemed to prefer his company to hers. - Sansa, AGoT
Sansa could never understand how two sisters, born only two years apart, could be so different. It would have been easier if Arya had been a bastard, like their half brother Jon. She even looked like Jon, with the long face and brown hair of the Starks, and nothing of their lady mother in her face or her coloring. And Jon's mother had been common, or so people whispered. - Sansa, AGoT
Of course, Jeyne had been in love with Lord Beric ever since she had first glimpsed him in the lists. Sansa thought she was being silly; Jeyne was only a steward's daughter, after all, and no matter how much she mooned after him, Lord Beric would never look at someone so far beneath him, even if she hadn't been half his age. - Sansa, AGoT
There is an actual canonical reason for why Jon and Arya always qualify their mentions of Sansa with 'EVEN Sansa'. There's a reason for that distance between these siblings.
And it's not just something that goes away either. Three books later and Sansa still doesn't get the class dynamics and understanding for why the hungry mob of small folk attacked the Lannister procession while loving Margaery/the Tyrells for giving them food -
“The same smallfolk who pulled me from my horse and would have killed me, if not for the Hound. Sansa had done nothing to make the commons hate her, no more than Margaery Tyrell had done to win their love.” - Sansa, AGoT
4 books later and Sansa is still classist and sexist while in the Vale. She is aghast at having to play a pretend bastard and complains about it to Littlefinger every chance she gets. She thinks Mya Stone is worthy of only marrying Ser Lothor Brune, the much older knight of low birth.
Alayne wondered what Mya made of Ser Lothor. With his squashed nose, square jaw, and nap of woolly grey hair, Brune could not be called comely, but he was not ugly either. Though he had risen to knighthood, Ser Lothor's birth had been very low. Brune would be a good match for a bastard girl like Mya Stone, she thought. It might be different if her father had acknowledged her, but he never did. And Maddy says that she's no maid either. - Alayne, AFfC
Why is Sansa going to like Brienne, when we know what she thought of Arya for not conforming and even in AFfC she says this about Mya Stone -
Mya's eyes were her best feature, big and blue. She could be pretty, if she would dress up like a girl. - Alayne, AFfC
There's a reason Sansa is close friends with high born Myranda Royce and not Mya Stone. Mya is just the worker who takes orders from her. Myranda is the girlfriend with whom she can gossip and have fun.
Sansa has compassion for the high born knights - the stuttering Ser Wallace, the wounded Ser Lancel, the drunken Ser Dontos of house Hollard - because they fit into her romantic songs. This is why she casts Ser Dontos as Florian -
No one can save me but my Florian. Ser Dontos had promised he would help her escape, but not until the night of Joffrey's wedding. The plans had been well laid, her dear devoted knight-turned-fool assured her; there was nothing to do until then but endure, and count the days. - Sansa, ASoS
That's the irony of the story GRRM has been telling. The outcasts of society - characters who actually follow the code of a knight - like Brienne and Ser Duncan - will never show up in the songs that Sansa loves about knights and maidens.
Sansa is not Arya or Daenerys or Jon Snow. She is not going to love Ser Duncan the Tall - the orphan who grew up in the slums of King's Landing. She is not going to think that Brienne - an ugly woman who does not wear a dress - is a great knight. That maybe Sansa in one's fanfiction or personal headcanons. However, that's not who the character is in the books. And that's okay.
