What's not to love.

Nightmare Moon and Luna are the same pony...
I love Cadance a lot.

I like Golden Harvest (Carret Top) as well..

Why? I honestly don't know.
She rarely has speaking lines, but appears in almost every episode as part of the crowd or whatever..
Dose that count?

Derp

I adore Golden Harvest/Carrot Top as well. I even have a hat with her cutie mark on it. :3 One of my favorite identifiable background ponies.

1. Fluttershy
2. Rainbow Dash
3. Twilight Sparkle
4. Applejack
5. Rarity
6. Pinkie Pie
7. Luna
8. Cadence
9. Shining Armor
10. Celestia

Please don't hate me, but...
I really don't like Derpy. She's overrated...

I agree with Tawnyjay on Derpy.

I like Derpy too, But I choose Fluttershy.

1. Fluttershy
2. Applejack
3. Rainbow Dash
4. Rarity
5. Pinkie Pie
6. Twilight Sparkle
7. Cadance
8. Celestia
9. Luna/Nightmare Moon
10. Shining Armor
11. Derpy

That said, some of them are really close. Fluttershy and Applejack are definitely my two favourites, and I love the other four of the main characters too. Then Cadance is definitely my favourite of the royal ponies. I like Celestia, Luna and Shining Armor about the same really, but I attempted to put them in an order. I don't have a problem with Derpy but she doesn't interest me as much as the other characters here. There are a lot of other characters I really like in the show too!