Voting for a candidate for governmental representation is an official declaration that you deem the person you're voting for accurately and effectively to represent you. In other words, when you vote for a candidate, you are unambiguously stating, "This person stands in my stead." Regard you yourself so little that you'll vote for someone who does not represent you?
The two predominant political parties in this country are thrilled that you've fallen into the "lesser of two evils" trap. It has allowed them to field candidates that serve the party and themselves first, and often exclusively. They don't have to field candidates who truly represent anyone. They just have to make their candidate look a little less bad than the candidate of the other party to a plurality. When you vote for Rick Perry instead of Barack Obama, you are serving the parties, and they are glad of it. If neither truly represents you, vote for neither. Either write in the name of someone who truly represents you, or don't vote in that election. Have respect for yourself and your views. Don't be a minion.