Favorites pick you.
^^this
It's all so clear now
Absolutely this.
My favorite is Blossom. She was my first pony as a child. Then I found a blossom plushie at a yard sale as a child. Then I got another in a lot with other ponies, I had planned on selling her because she had a hair cut. But once I cleaned her and styled her it is such a cute little bob i had to keep her. Then I saw a custom g1-g4 blossom by Okami_Amaterasu that I just had to have.
....Then one day I woke up and thought "Where the heck did all these blossoms come from?! And yet, it just seems right...
As far as my other favorites it just happens. I dont choose them. Some of them surprise me, like leaper. I didnt like him in pictures, had no intention of getting him. But when I got him with a lot I fell in love with him.