Idunno, I saw this on a couple pages and thought I'd do this.

Mane Six:

Top Tier:
Twilight and Dashie tie for first place. Please don't make me choose! I feel that I relate to both of them on a very fundamental level, but I can't tell which is my absolute favorite.

Middle Tier:
Applejack, Fluttershy, and Rarity are all great, relatable, accomplished mares. I don't enjoy seeing them quite as much as those first two, but they're pretty fun.

Bottom Tier:
Pinkie Pie. Go home Pinkie. You're drunk. Pinkie stahp.

Princesses:
Top Tier:
Luna! Long live the New Lunar Republic!
Middle Tier:
Celestia and Cadence. Not sure...
Bottom Tier:
At the end of season 2, Cadence lived down here, but season 3 seems to be repairing her character. We'll see.

Background Ponies:
Top Tier:
Derpy Hooves and Time Turner. A perfect pair of ponies, if you ask me.
Middle Tier:
Lyra and Bonbon.
Bottom Tier:
I can't think of any background ponies I dislike...

Villains:
Top Tier:
Discord and Queen Chrysalis. These bad mother-buckers are fantastic. Good, strong, well-written villains who really push the envelope on how good a villain in a children's cartoon can be. Plus, their laughter is great. I can't help but giggle along with QC at the end of 'This Day Aria.'

Middle Tier:
NightMare Moon. At least from what we saw of her in canon, she was a bit trite, and far from the best villain I've ever seen. Not bad, though, and plenty of room for redemption in fanfiction.

Bottom Tier:
Ol' crystal-boy. He had some tough acts to follow, sure, but he didn't really handle it well. Evil grunting just isn't scary. Neither is saying, 'crystaaaaaals'.