hmm... I can't pick just one OC as a favorite. I've made many characters and have chosen favorites for different things.
But if I absolutely had to pick just one OC as a favorite, it would be Sparrow (I don't have artwork of her uploaded yet)
In my upcoming story, Hybrid, there are immortal beings known as Reaper Shadows (my idea. i'm getting to the explanation part)
Each Reaper has their own Shadow for a "battlefield companion" of sorts (similar to Weapons and Weapon-Meisters in Soul Eater)
Reaper Shadows are Feline/Bird Humanoids that inhabit the Void (along with other Spirits that end up there)
Each Reaper Shadow has a nickname that is also the name of a type of bird. A Reaper Shadow's nickname is created by the initials of their full name (for example, Sparrow's full name is Sophia Penelope Alaina Rochelle Rose Octavia Whitney, and her initials spell out 'SPARROW')
Sparrow was the first Reaper Shadow I created, and was originally just a random drawing in my sketchbook. But when I gave her a name, drew her next to a Reaper character I drew, and later created other characters that were the same kind of being as her, I ended up creating a new species of beings for my story owo"
As for Sparrow's overall character, she's nothing really special. Sure she's a great leader, friend, teacher/mentor, and is quite skilled in her abilities, but she's got a bit of a temper, can be stubborn, determined, ambitious, and competitive, and usually isn't on the "good guys" side.
She's no Greater Good, but she's no Greater Evil either. She's just your average, ambitious girl with great abilities, a stubborn/competitive streak, and a quick temper.
Plus I always love drawing her character... repeatedly owo"
So yeah, if I had to pick a favorite OC, it would be Sparrow, and ^that's why