Personally I am a fan of logistical taxation, where the mean income (including capital gains) pays 50% in tax and every standard deviation σ above (or below) pays extra (or less) according to 1 / (1 + e^-σ).
What will happen with this taxation is that if everybody makes the same income, then everybody pays 50% in tax. If some rich dude is making a lot more money then everybody else, they will lower the tax for everybody else while paying a lot more them selves. At some point (say 3 standard deviations above the mean) you end up getting less after taxes then had your income been lower (say 2 SD above), in other words, the limit is 100% tax for extremely high incomes (and 0% for extremely low incomes). That is, I favor a system that has maximum income, and you are actively punished for making more.
What will happen with this taxation is that if everybody makes the same income, then everybody pays 50% in tax. If some rich dude is making a lot more money then everybody else, they will lower the tax for everybody else while paying a lot more them selves. At some point (say 3 standard deviations above the mean) you end up getting less after taxes then had your income been lower (say 2 SD above), in other words, the limit is 100% tax for extremely high incomes (and 0% for extremely low incomes). That is, I favor a system that has maximum income, and you are actively punished for making more.