Merle Dixon. Also, though I know it'd be stretch since you barely if ever see her and she's still very young, but are you planning on drawing Asskicker/Judith? A drawing of her and big brother Carl together could be teeth-rottingly adorable.

Wibble and Wobble are a close second, but Andrea is my favorite of the bunch. The way you described not having a cutie mark really fits and that jacket does look great on her, too.

Again, Andrea, specifically her mental transformation throughout the show.

Finally, future predictions and/or flashbacks [before Rick woke up] could be cool, too. Like what the Govenor was doing, Glenn's experiences before he joined the first group, etc.

I haven't ever seen walking dead much but still your style is pretty unique so i think all the character but if I had to choose maybe the black dude from the walking dead game or maybe Clementine the little girl?