XxSlayerxX said:
My answer for this question would definitely be Buffy. To come up with this I tried to think about all of the attributes of a slayer; strength, will, power, motive.... This list goes on.
When Faith fights, she does it in order to feel powerful, that's her only motivation. It's all she has, the only thing she can control, and not always. Things have never gone her way in life, but by kicking butt, she can, at least for a while, feel like she's in control of things, feel powerful. This can sometimes be an asset, making her less hesitant and sometimes more determined, but it can also be her downfall. The determination doesn't come from the right place, she has no real moral compas to guide her, only her need for power. Powerful, yes, but also volatile and not grounded. There is no guarantee that she'll do the right thing... Only the powerful thing.
For Buffy, there are other motivations and reasons behind the fighting. She doesn't fight because it makes her powerful or because she's the slayer. She fights because she IS powerful and has the ability to change things in the world. It's what a person does in this world that defines them, and for an able person to do nothing is to be irresponsible and apart from humanity. Humanity is what grounds Buffy. Her friend and family, while unusual for a slayer, are what connect her to the world and give her motivations and purpose. Without ties, loves and reponsibilities, all a person has is themself, and without the things in life that defines one's self, that's not much.
This is why I think that Buffy is the better slayer. In the end, she's not just fighting for herself, but for connections to the world. She has a much more inspiring, and I feel more powerful, motivation. Plus, she's a little more stable, but hey....
Also, excuse the random, fragmented thoughts, it's late and I'm all jittery and caffinated.