I think mine is Chuck's quote, being:
"I don't know much about you folks, but you keep goin' on like this, and that girl ain't gonna make it. You've got to think of her as a living person. That's it. You ain't little. You ain't a girl, you ain't a boy. You ain't strong... or smart. You're alive."
I just really liked that quote, it showed that in the apocalypse it doesn't matter how young you are, how smart you are, how strong you are, or who you are. The world doesn't care any more. You're either dead, alive, or undead. It's a really well written quote and it really changed how I took care of Clementine, instead of trying to shelter her.