I'm a fan of flat income tax with flat, per-person guaranteed income. Set the tax rate and base income so that the changeover is revenue neutral, zero income people are a bit better off than currently, and the 90th percentile pays about what they pay now. Billionaires will end up paying way more. (In this proposal, capital gains are treated as regular income.)

The beauty of this is that now you can add astronomical consumption taxes, and just plow the increased revenue into the guaranteed income pool. On average, the consumption tax is revenue neutral for the government, and (as a percentage of income) disproportionately goes to the poor.

Also, you can eliminate 99% of the US tax accounting industry, food stamp program administration, and all sorts of other bureaucracies.