Mixed-Member Proportional Voting (with the 5% threshold caveat) is what I generally think would be best for the United States at this point in its history. Winner-take-all single districts aren't a bad idea, and they do foster political centrism, but in a nation of 285 million people, I don't think the "mushy middle" approach is viable anymore. Every year there is a refrain of "no choices," and the "mushy middle" approach politically has not seemed to payoff in a more amicable and less partisan broader culture, rather, it just enforces "best fit" politicians on perennially unsatisfied constituencies.