That question was answered here, in my post of 4/22/11 9:56 AM.
The Gemora that says נמנו וגמרו נוח לו לאדם שלא נברא יותר משנברא would indicate that it would have been best not to have been created. So how could the reason for creation be להטיב?
It's like working for a company that takes a little off your paycheck every month to invest in the company's stocks. At payday, you may complain, and try to make sure they take off as little as possible. But when the stock goes through the roof, the only complaint you will have is that they did not take off more.
So if G-d knows me so well don’t u think he would have known I don’t want to be here, so why does he put me through this,other people want to live in the world - let them, but why me? Doesn’t He care?
So too, you may think, now, that it was not in your interest to be created. But when you see the fruits of your Mitzvos, the only complaint you will have is why you were not given opportunity to do more.
See this forum for the same idea in a different context.