I like this author's answer.

I would end injustice, considering that justice is mutual respect (of basic kind: taking one another into account as we live our separate lives together in this world). That translates into a handful of absolute prohibitions: no killing, harming, coercing, stealing, or manipulating (lying, cheating, etc.) to get what we want. Take away all that, and this world would be a pretty decent place.

By the way, mutual respect can be applied to the political process and the economy, yielding a democratic political process and making the existing economy (any actual nation's existing economy) fully self-regulating, with no unemployment, poverty, taxes, or public debt and more sustainability — yet still no limit on income/wealth.