There are two separate issues: what to display and how to sort comments.
LessWrong displays the net number of positive votes; and, if you hover your mouse over the score, also the proportion of upvotes.
It offers several ways to sort the comments, mainly copied from Reddit, which now offers fewer ways. Go up to the top of a post. Just above the comment box, on the right, but below the tags is a triangle and the words "Sort By," probably "Sort By: Best." Click on the triangle and you can choose among Best, Popular, New, Controversial, Top, Old, and Leading. I think Top is net score. I'm not sure what is the difference between Popular, Best, and Leading. I suspect Leading is closest to what you suggest. Once you make a choice, all posts will be displayed that way until you choose again.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should start on Monday, and end on Sunday.
4. Unflag the two options "Notify me of new top level comments on this article" and "