If nothing else from her, then definitely "Mine" and "Sparks Fly".
"Change". Taylor's account of her and her band's struggle to be noticed- with a note of confident triumph. Taylor's dad convinced her that the song could be applied to other people and events- and it's a fitting closer to "Fearless". "...and we'll sing hallelujah."
"Long Live". The melody came to Taylor while she was touring for "Fearless" hearing the screaming crowds.
"All Too Well", certainly the Grammy performance at least. The emotional intensity she conveys simply by singing and playing the piano works incredibly well.
Not technically by Taylor Swift, but this parody of "You Belong With Me", sung from the perspective of Mass Effect's Tali. Cute, yet somehow saddening ...
The bridge to Treacherous.
Two headlights shine through the sleepless night And I will get you, and get you alone Your name has echoed through my mind And I just think you should, think you should know That nothing safe is worth the drive and I would Follow you, follow you home... I'll follow you, follow you home...
"I Knew You Were Trouble" Live. Watch videos of it on Youtube; the entire crowd are absolutely roaring the chorus at the top of their lungs, and the final note is ridculously high and held for two counts of eight. Many critics consider it the highlight of her Red Tour.