In the first place, NEVER base your decision on which bird to get by beauty. This could be a disaster for you and the bird. You need to consider which bird would fit your lifestyle best, then the peronality of that particular species and requirements. Out of the two you selected, I would choose the Macaw. Cockatoo's don't handle being alone for long persiods very well. Also, where do you live, an apartment, house ????? How will your neighbors feel about getting a bird such as a cockatoo or Macaw. They will have to live with the noise just as you will and both species are LOUD!
I like to check You Tube on bird videos if I'm thinking about a particular bird. Check out Screaming Macaws or Screaming cockatoo's to give you an idea of just how loud they can be. Turn your computer speakers all the way UP to get the full effect. When you do this, just think, this is what you will be living with the rest of YOUR LIFE. Because owning a bird like this is a life time commitment.