A friend of mine had given an advice to me regarding this question.
He said that this is a common question in job interviews and according to him, the only way to answer this question is not to answer it at all.
He said that this is not the actual question the interviewer would want to ask you. Instead, he is asking on why the company should hire you. Come to think of it, the company does not want to know your special quirks like drinking 21 shots faster than the 21 guns salute. On the way to my interview, I kept on thinking on this question and it seems like I can't really form an award winning answer for this type of question. I had made a mental note on my good qualities but when I formulate an answer, it always sound boastful and proud.
Luckily, on the actual interview, the question was not fired. The interviewer asked me straight to the point on why they should hire me. I answered him truthfully focusing on my value instead on my uniqueness with a dash of my flaws here and there. My value make me worthy of the position but I guess my flaws made me unique.