Which is better: to perform the obligatory Hajj for the first time, or to donate money to the displaced people in Iraq?

Feeding the needy in conflict zones like Iraq and Syria is among the best forms of charity, and it may even reach the level of a communal obligation (fard kifaya). If your Hajj is obligatory and you are able to perform it, then prioritize it over charity. If you have already performed the obligatory Hajj, then charity is better.