My favorite is Big MacIntosh. I just like how he's a pony of few words.
Out of the mane 6, Pinkie is my favorite, closely followed by Twillight and Fluttershy, because they are the 3 that I have the most in common with. Pinkie represent my crazy side, how I can be random, how I love to have fun and how I want everybody around me to have fun, laugh and smile. Twillight represent my bookworm side and how I like to learn new things. Finally, while I'm not as shy as Fluttershy, I do have my shy moments but the main reason why I'm similar to Fluttershy is because I'm very kind and extremely hard to anger but if somehow, you manage to anger me, you will wish that you didn't. I can do the Stare as effectively as her...
Granny Smiths is also one of my favorite for being a lot like my grandma.
Out of the background ponies, my favorite would be Derpy, DJP0N3 and Doctor Whooves.
I also like Flim and Flam a lot, 'cause they were fun, but they weren't choices in the poll so...