I don't have specific username recommendations, and I doubt if I'd follow anyone at all on HN since the threading format and the UI aren't good enough to follow long discussions. However, here are two points to start with for anyone interested in something like this, or creating an external service that notifies people of comments by the followed users (disclaimer: I'm not associated with these and do not endorse them, so try and decide for yourself):
1. The HN karma leaderboard at https://news.ycombinator.com/leaders . You can find the list of people ordered by karma points, from highest to lowest. Obviously, the ones at the top have contributed a lot of appreciated content here.
2. HN Profile at https://www.hnprofile.com/. Use this to find an expert on a specific topic by just entering it there and hitting Search. This site has been submitted here as a Show HN more than a few times. You can browse through the comments by the users in the search results and decide.
All the ones which I have in my "about" section in my HN profile, especially when they talk about topics that are in the parens next to their name on the list.
The question is not suggesting a follow feature. It is just a hypothetical. The aim is to list great contributors on this platform, so that anyone looking at this thread can learn something new from their contributions.
1. The HN karma leaderboard at https://news.ycombinator.com/leaders . You can find the list of people ordered by karma points, from highest to lowest. Obviously, the ones at the top have contributed a lot of appreciated content here.
2. HN Profile at https://www.hnprofile.com/. Use this to find an expert on a specific topic by just entering it there and hitting Search. This site has been submitted here as a Show HN more than a few times. You can browse through the comments by the users in the search results and decide.