Rarity - ooo, so many good moments... but finest hour?
"Secret of my Excess" has to rate up there. Rarity gets kidnapped by a dragon (actually a grown-up Spike (one version of such at least) although she didn't know that at the time) and tells him off for ripping her cape (a crime against FASHION!), refuses to give over her Fire Ruby because it was a gift from Spike, and even challenges him to eat her if he wants (it was offhand and she probably wasn't serious about it, but still, you have to give it up for my girl's bravery.) Then finds out the dragon WAS Spike, starts falling to her death along with him and still responds to his attempt at telling her his feelings for her with a gentle hoof to his lips. Then when rescued, she tells him he's a hero and cheers him up with a kiss...
It's just a pity that the writers didn't know how to move that whole Spike Crushes on Rarity plot line along for at least the next four seasons. (I haven't gotten past Season 6, unfortunately... but I am on holiday, so perhaps now is the time to finish watching the series.)
Honorable mentions:
Threatens to tear a trio of teenage dragon to pieces for threatening her Spikey-Wikey - so brave.
Is willing to give up her tail to make a sad river serpent happy - so generous.
Smacking Changelings in the face with an awesome right hook - so right-hooky?
Is personally asked by Sapphire Shores to create her wardrobe for her latest tour based on rave-reviews of her fashion in Clothes Horse Magazine - so dreams-coming-true.
Opens multiple shops in Canterlot and beyond - so more-dreams-coming-true!
I could go on for hours, but this isn't my blog, so I won't!