The US Government and blacks.
Whites have been given more free stuff than anyone else.
You do realize that 1. they would need to figure out who is black and who is not (there are a ton of white people who have some African blood, for instance), 2. they would need to figure out which portion of the taxpayers needs to pay, meaning they would then need to figure out who is white, who is not, whether brand spanking new immigrants from Europe should need to fork over their money, etc. Do Indians pay? Chinese? How exactly is this going to work? Are you going to track down all the descendents of former slave owners and only charge them? 3. exactly how much money is this supposed to be? Would it even be money? Would black people actually spend that extra money wisely? Probably not (for the record, I don't think white people would spend extra money that randomly finds its way into their pocket wisely either). People value things they earn. That which is not earned is quickly spent or thrown away on useless junk.
Then the government would probably be getting sued left and right by people who don't feel their tax dollars should be going to others when they were never slave owners and the others were never slaves. It would be an enormously complicated, expensive, and divisive endeavor. Not even close to being worth it, considering the money would rapidly be wasted anyway and things would go right back to the way they were before.