Whose Income to Tax?

Pretend for a moment that you've just been elected to public office and that you now have the power to choose whose income you're going to tax to pay for all the vital government programs you believe should be supported. If you want to keep those vital government programs on a sound financial footing, without jeopardizing the well-being of the people who rely on those programs in hard economic times, upon whose income should you most rely for your income tax revenue?