Africa is certainly the most exploited continent. I do think it is also the poorest continent, but this is because Western nations have exploited Africa remorselessly for hundreds of years. Africa certainly has huge natural resources, and would be much wealthier were it not for Western interference.

A bit of a tangent, but Africa does suffer from geography to an extent. There is a question as to why in the past Africa has struggled to develop as quickly as other nations. I think this is due to the fact that the river system is not easily navigable. Particularly compared to say the USA, which has easy river navigation throughout the country. Africa's major rivers on the other hand have frequent disruption from waterfalls and rapids, which significantly hampers trade and development. Apologies if I'm veering off-topic slightly, but I think this is an important point historically.