In my perfect, dictatorship world, I would do both. I would find some value that fits the “bare minimum” income someone could make. This could be 0.5FTE at minimum wage, for example, and set that as 0%. I would then fix the tax brackets to inflation, add an extra bracket to the top 1-2% income earners. I would lower GST back to 12.5%, enact a CGT (which I prefer over a wealth tax if it targets assets), and tinker with teh rest of the tax code to close as many loopholes as possible.