I can see where you'd get this impression, but--
Bai Meizhen and Sun Liling have both been raised to believe that much of the rest of the world is their enemy, and they have personally experienced losses that back up that view, and both of them entered the sect with notable social flaws due to that. Both of them even picked up an uncommonly talented street urchin with their own serious social defects!
And after all those carefully set up parallels, you think we just happened to blindly pick the one who is more intrinsically good? I'm pretty sure Yrsillar is a better author than that. For all that Hobbes is bullshit, Ling Qi herself has said more than once that the ability to be kind and good is something that desperation and pain take away from you. Bai Meizhen has succeeded in cultivation and in socialization, and as such has had people there to help her rise beyond her own worse impulses. Sun Liling has failed again and again, and so she's only fallen deeper into her own worse self.
People make choices, but some choices are made for you by your circumstances, and that makes it harder to choose right when you could still correct your course. Don't sell your sense of empathy so cheaply.