God I hate the term "bad-ass". Sounds like something people would call themselves in an American reality show.
Anyway, back to topic. I would have to say that my favourite female lead at the moment is the new Lara Croft.
Despite being rightfully terrified, she still presses forward and overcome challenges. That says a lot more to me than some sociopath that feels no fear or remorse.
In the same vein, I love Chihiro from Spirited away. The way she faced fears and did what she needed to do to save her parents.
Prior to that, maybe Alita from Battle Angel or Deunan from Appleseed.