Obviously any compensation, if any should be paid, should be paid by all the parties responsible. This makes it a little more complicated, as it would be very hard to trace the Africans or Arabs who actually took the slaves (not many slaves were actually captured by Europeans or Americans). Then of course, due responsibility has to be bourne by those who carried the slaves. If someone can trace the shipment their ancestors came in on, then there are records of crew and companies involved, from a number of nations, Great Britain, Holland, as well as the States. Some of the people would be unable to pay, as they would be poorer than those that were claiming.
If such compensation is paid, then indigenous people who have been disadvantaged by invaders will likely re-double their efforts to claim for compensation, or re-start claims that previously failed.
The statute of limitations is also something to think about. If white Americans and others whose ancestors were involved in the slave trade have to pay, and all the indigenous peoples' claims are reviewed, and in light of the success of those with slave ancestors, then other even more historically distant disadvantgees will perue their claim. Those of Jewish ancesotory alone have a millenia of severe discrimination and suffering to be compensated for by anyone whose ancestor was a Christian, and all those in Britain who could prove they were Celts would be able to retire, as the invaders would have to pay them compensation too.
Obviously the idea of compensation for sins vested upon ones ancestors, no matter how apealling on some levels, is completely ridiculous on practical levels. Even if it were paid by central government, people who had no part in the slavery would end up paying as much extra tax as those whose ancestors were involved, which is not good, especially since some of them would be just as poor as those that the money was intended for.
What should happen is that those who are disadvantaged by reason of their recent background, the poor, should be helped to overcome the disadvantages of their background so their children will have the same opportunties as most people. Regardless of what colur they are.