Highest rated-Christa, sounds good but it appears to have an obvious flaw, that is, Not everyone gets to rate every comment. 

Since i (or anyone) do not get to rate (exposed to) every single comment, how do you know that one is actually rated higher ?  the rating is restricted to only those particular people that are required to vote a particular comment.  You can have all of the algorithms you want, but what it ultimately does is selects /restricts a certain few comments to be seen by a certain few people and those few people are deciding to rate it or not.  If you happen to show my comment to 30 people that absolutely disagree with most of what i say, they will never rate it high. But in contrast, if the remaining 70% of the people that did not get asked about the comment would have liked it, it ignores them and my comment is not rates the same that if all commenters to an article see the same comment and all of them decide to give it a high rating.