Ah, a place to list my issues with Celestia
In all seriousness, though, I don't think she's the greatest leader, and the society she runs is not perfectly utopian by a long shot.
1. "Absolute power corrupts absolutely." History has shown this, and yet Celestia has been in sole power since Luna became Nightmare Moon. Be warned, ponies. I'm not saying the show will make this happen, but theoretically it could. To expand on this topic: a) following Luna's return, she was not given her equal position with Celestia back. In addition, she remained smaller and weaker. b) who the heck is Cadence, and where does she come from? If she's an alicorn as well why does she wield no apparent power, and associate with common unicorns as a child? I've concluded that Celestia is basically hogging the power here.
2. Like dragonkiss said, there is a clear division of classes. I think it can be seen especially in Canterlot vs. Ponyville. The Canterlot ponies treat Ponyville ponies like dirt.
3. Although it isn't officially stated, Celestia seems to be pretty much dictator for life. But woah there, she's immortal. So Celestia = dictator for life + immortal? Not equal opportunity at all.
4. Equestria seems to be a capitalist society, like dragonkiss's examples of Fluttershy's day at the market and Flim and Flam nearly buying Sweet Apple Acres.
5. Another way ponies aren't equal is the fact that Equestria is quite obviously a female-dominated society. As far as we know, there are no male alicorns; the highest rank for a stallion we've seen to date is unicorn princes (Blueblood and Shining Armor), and even the mayor of Ponyville is female. Applejack runs Sweet Apple Acres, not Big Mac, and Rarity is an entrepreneur as well. Rainbow Dash holds a job, as does Pinkie Pie, (whether you consider it a job or an apprenticeship; that's not quite clear) and Twilight is receiving what is arguably the highest education in all of Equestria.
6. There is most certainly not peace in Equestria. Obviously.
That being said, the Mane 6 definitely embody equality, fairness, respect, etc., but in my opinion, Equestria on a whole does not, and a lot of episodes, such as Sweet and Elite, seem to show the Mane 6 facing that.
*gets off soapbox*
Good luck with your paper, Pinkie! I almost wrote a paper myself there, concession and all. Gosh, I'm chatty today.