There is no better way to add value to a blog post than to get genuine comments on the blog post. Which comment system do you use ? How does it help ?
I see that Disqus is very popular among high traffic blogs. As you know, WordPress has a built-in comment system which you can use if you don't want to add more code to your blog which is already heavy.
admin I wouldn't use Disqus. This will cause you privacy issues and you won't actually host the comments yourself by default. One of the best commenting system replacements for WordPress is wpdiscuz
Lots of features, cute UI
I think this one is promising.