In the Netherlands there are about 13 political party's to choose from. More choice means that you can vote for the party you most believe in, and there are party's with a high moral standard among them. There are strict rules regarding campaign contributions which prevents conflict of interest.
Also there isn't one party who gets a majority, but multiple party's have to work together. Which means that in practice multiple party's achieve some of their goals and not just the largest one. The opposition can still propose laws and they can still get the accepted if they receive the majority of votes.
I assume that in America with only 2 choices, chances are quite large that at some point there just isn't a party to your liking..