Bad answer:

I am the best candidate for the role.

A good answer will reiterate your qualifications and will highlight what makes you unique.

Good answer:

I have been a firefighter for the past five years, my boss has said time and time again that without me, the department would not function so well. I have also taken the time to educate myself on some of the non-standard techniques used in first response. I can react quickly in hectic situations, and can handle the responsibilities of a leadership role. What is good enough for most people is never really good enough for me.