The Reddit voting system works fine. On both Reddit and HN I usually learn more from the comments than the actual article, but I still wouldn't want comments in the New York Times.

Heavy handed censorship turns rude commenters who should be simply ignored into internet terrorists, Facebook comments dilutes the conversation by making people self consciously edit themselves and Twitter or Tumblr replies are like shouting into the wind.

Good old semi-anonymous Reddit comments still perform though, even with a user base of millions of bratty kids the best stuff usually floats to the top.