I just started watching MLP a couple of weeks ago (I just made it to season 5). And holy poop Rarity is 100% straight up my favorite pony. During season 1 she was tied with Twilight for my favorite but season 2 onward she's has been and still is my #1 favorite.
She's pretty, she's motivated and determined, she's hard-working and artistic, she's confident, she has class and poise, she's clever, charismatic, and funny. She also has a beautiful voice.
I just admire her so much, and I wish I could be more like her in certain ways. I love all the main six but Rarity has a special place in my heart.