What, during your interview, do think was the main reason that you got hired?

I have generally known the exact point during the interview that the decision had been made to hire me. In each case it was because I perfectly fit the unspoken needs the employer was looking for.

At the same time, I was well aware of the very answer that lost me the job in unsuccessful interviews. Generally when my confidence in my abilities was seen as cockiness.

Honesty!

You get hired because the interviewer (most likely your future boss) made the decision. Decisions come from the gut with input from the brain and heart. So the total package you put in front of him/her was the best of all worlds given the pool of people sifted through. So the interviewer is assessing whether you'll be a help or hindrance, supportive or not, cultural fit or not, etc. Interviews are like professional skating. Your technical skills are the short program and the kind of person you are is the long program.

Watch out for desperate hiring situations, either way. It will almost always guarantee and parting of ways and you'll have wasted another 18 months getting to where you should have been.