Though, even if that is the one and only thing you grade on, there are still differences between the parties. While both have certainly protected corporate interests to some extent, Democrats have been the party more interested in campaign finance reform to reduce the effect of money in elections, the ones who protested and have tried to reverse the Supreme Court decision to designate corporations as "people," the ones who have tried to push through regulations on Wall Street. That hardly makes them pristine and without sin, but they still do more for the one thing you care about than Republicans. Saying "I don't care about better if it's not perfect" gets you even less of what you want.