You can measure the number of replies, but not the quality of them.
Maybe your initiative could keep a tab of users that leave great comments. A score card of a kind.
But listen, I agree. This is not easy to think about about, hence why I'm putting it out there.
Our weekly report has the top 20 most upvoted Hivers. We upvote a lot of commemts, but there are also a lot we don't upvote.
All the different things together would make someone a great contributor to the chain.
I've slept a night over it and came up with and idea.
Maybe you could do something with a badge or maybe even multiple badges for people that contribute to the growth of Hive.
You could set up a diverse team that decides who should receive a badge.
You could measure all the things you mention in your post and 'the team' can nominate people who they think receives a badge.
And when a user stops being active or 'misbehaves', you could just remove the badge.
In PeakD the badges are shown next to your profile. I other interfaces they aren't (yet).
I do like the idea of having badges for this, for sure. Maybe talking with @arcange is a good start.
I see @arcange is a guest in the HIVE THRIVE podcast next week. Maybe a nice topic to discuss there too.
Oh yes, fo sho!