This is the graphic I've been waiting to see, a side-by-side comparison of the income tax plans proposed by camps McCain and Obama (Thanks to Sheila O.K. for sending this my way from the Washington Post). As you can see, the McCain plan provides tax "relief" to all Americans, but the Obama plan provides the most relief to the middle and low income brackets. In essence, the Obama plan creates parity for those who have been shouldering the Bush (and presumably continued by McCain) induced tax-cuts.
According to the recent Tax Policy Center study, both candidates' plans would increase the national debt. However, Obama wins here on the fiscal conservation front: McCain's proposal would cost the Treasury $3.7 trillion, while Obama's would cash in at $2.7 trillion.
The power of the purse ultimately rests with Congress, and neither candidate would be able to singlehandedly change the course of economic policy upon taking office. Still, when it comes to taxes, Obama and McCain would guide the country in sharply different directions.