I think Derpy Hooves is best pony. Not necessarily for her character, design or personality (although the versatility of those three certainly adds a lot to her charm), but because she represents our crowning achievement as a community.

The legacy of Derpy is one that will no doubt be discussed in years to come, by media and perhaps sociology lecturerers. The creation of Derpy as a character was a result of us being crazy about the show, and the fact that a little girls' show managed to capture the minds of teenage/young adult males to that extent is enough to warrant some sort of legend as it is. The the fact that this animation error's personality was noticed by the production team also says a lot. But the fact that they liked her so much that they not only began referring to her as Derpy in the official storyboards but also stopped all the presses to put her Derpy eyes in the show itself says so much about what we can now achieve through the Internet.

Derpy Hooves represents the closing gap between old media and new media. Up until now, what we watch on TV and in films, what we read in the news and hear on the radio has been kept solely in the control of those channels and the companies who own them. Derpy is directly a result of the viewers' intrest in the show. She was created by the bronies and thanks to our communication with those who create the show, an idea of ours has become part of it. Adventure Time also do this to an extent (with the gender-swap characters) which is just another sign of the changing times.

Derpy is more than just a googly-eyed background pony. She is more than an in-joke between the team and the fans. She is a repercussion of our influence as a movement. She is a sign of a changing world. She is a sign of new voices being heard where there weren't before. Derpy is us. Derpy is best pony.

She's also really cute.