The toughest interview question?

I hate the question as to what is your greatest weakness. You have to guard your words carefully because they are looking to see if you fit into their environment. I remembering acing an interview, or so I thought, until this question came up. I said something like I have been frustrated waiting for answers. In hindsight, I can see that this can be an issue with most companies and that probably was a deal breaker. Being prepared for this question is crucial.

it's the same question that i will always ask when im conducting the interview...hehe...it's 'Why do you think we should hire you?' it's so annoying...i cant self praised too much yet i cant step on myself...it's hard to be at the centre.