I have noticed that a lot of people think that the prophecy of Cersei being defeated by a younger and beautiful queen and taking everything that she hold dear, are Daenerys ore Margaery. I on the other hand stand firmly behind that prophecy is about Sansa.

The Parallel between Sansa Stark and Cersei Lannister arc

Sansa and Cersei are not completely similar, no. But they are in the sense that Sansa shares, at the beginning of the series, many qualities with a young Cersei. We know from the text and from backstory from Jaime, that Cersei was a very idealistic young girl. She dreamed of being a queen, wanted to marry Rhaegar, and believed in the songs and stories. This is no different from Sansa who wanted to marry Joffrey upon seeing him. Sansa’s narrative runs parallel to Cersei’s. She too was a young girl who idealized the songs and stories of Westeros. She too fell in love with a prince. The only thing Sansa Stark wanted at the beginning of the series is to marry Joffrey and become queen. And like Cersei, Sansa Stark finds herself losing that perfect bubbled world of charm and love. From her journey to King’s Landing, with the incident with Nymeria and then losing Lady, and then from there in King’s Landing to the death of her father, Sansa has her world torn apart and reshaped. Even after, she falls into marriages that show her the same that Cersei was treated to; and the constant abuse that she suffers from Joffrey and his Knights. She sees Westeros for what it is, understands the game that is being played here. She no longer believes in songs, or rather, she sees that you have to make your own song, your own story, by the actions you choose and the things you do.

Though they started quite the same, Sansa will never be like Cersei.

Cersei lost herself into the Game of Thrones. While I see Sansa being a natural politician, getting more edgier as the learns the game from a true master I still believe Sansa will maintain the idealistic and purity of her character. This is why Sansa is the younger and beautiful queen. It is not all about appearance, but the beauty of their personality of not being greedy for power. Sansa is to humble for that.

Sansa took two things from Cersei she dearly loved:

Joffrey: Sansa is partly responsible for his death
Jaime: He sees Sansa being the key of regaining his honor so he joins with Brienne to seek her.

Plus this would be the right sense of karma and justice for Cersei. Wouldn't this be deliciously ironic that the girl that Cersei thought as weak and stupid will cause her demise.

It would be poetic.

Disclaimer: The most information I got at the Sansa and Cersei comparison is this amazing meta of this tumblr person: