A feminist would celebrate the show My Little Pony: Friendship is Magic.
The first reason a feminist would celebrate this show is because it has a large, diverse cast of female characters. The six main characters have a variety of interests and personality traits, and while this occaisonally causes conflict, they all play off of each other nicely and have good chemestry, which is an important thing for making a show entertaining. This is a large improvement over many forms of entertainment where female characters have the most importance when they are the love interest or relative of a male character- in fact, it seems to be the exact opposite in this show, as evidenced by the character Big Macintosh, who until recently didn't have much signifigance beyond being the older brother of Applejack and Apple Bloom, and when he finally got an episode where he had a signifigant role in the plot of an episode, it was the Valentine's Day episode (Hearts and Hooves Day) which was all about his love potion-induced romance with Cherrilee. This show's large and diverse cast of female characters is one reason a feminist would celebrate My Little Pony: Friendship is Magic.
The second reason a feminist would celebrate this show is because the portrayal of female characters is positive overall. While there have been episodes with female one-shot villans (like Boast Busters, which saw the one and only appearence of The Great and Powerful Trixie, who became a fan-favorite despite her arrogence and exaggeration), and episodes where the six main characters have made major mistakes (like Sweet and Elite, in which Rarity lied to the Canterlot upper-class in order to get accepted, and then to her friends in order to hide her ill-gained status), the overall message remains positive. All the main characters are shown to be independent and able to hold a sucessful job relating to their special talent, and are willing to overcome their faults for those they love, as shown in Dragonshy, when Fluttershy, the quiet and meek pegasus, yells at a dragon and gives him a death stare after he had assulted the other main characters, even though she's terrified of full-grown dragons. This is another reason a feminist would celebrate My Little Pony: Friendship is Magic.
In conclusion, a feminist would celebrate My Little Pony: Friendship is Magic.