Back to voting: I'm gonna say "Mystery" again.
And getting to the "well there are other nations..." No. Doesn't fly. When the "namby-pamby Pony Princess" controls those big balls of light that all things depend on for life, you can't say Ponies aren't dominant.
Griffons and such would make sense if they were some sort of fringe society, like Elves and Hobbits are in
The Lord of the Rings. But the show doesn't go with that. It has them casually mixing with pony society. We have a freaking minotaur selling self-help to an all-pony audience (implying that he's a part of and somehow works within the pony capitalist system), and a Donkey being at the Grand Galloping Gala. Stuff like that just doesn't mesh.
I mean take for example, the Diamond Dogs actually work. They clearly operate completely outside Pony society, have their own way of doing things, and to all appearances aren't very numerous. Dragons as portrayed in "Dragonshy" are credible—they're basically on the same level as The Hobbit's Smaug if Smaug could be talked down by yellow cuteness. As portrayed by "Dragon Quest, " they can't be taken as anything other than a slap in the face.
Also, guys, learn what "Racism" means. "Racism" would be if I favored one kind of pony over all others.