Between Pinkie Pie and Fluttershy who is the "bitch" of the Tamers Mane 6?
I know it used to be Rarity but ever since Rarity became best friends with Twilight she's been elevated to Mane 3 status in the Mane 6 with Twilight, and Rainbow.
Aplpejack is just kind of there in the middle not really getting abused but also not really getting acknowledged.