Kelvin Ng

This plugin enables blog owners to allow some shortcodes to be used in comments. You can choose what to allow (i.e. Whitelist some shortcodes). It only affects shortcodes in comments, but not in pages, posts, etc. All shortcodes are default to be disabled.
<a href="http://www.kelvinblog.tk/my-wordpress-plugins/shortcode-in-comment-page" rel="nofollow ugc">Plugin Homepage</a>
<h4>Settings</h4>
<ol>
<li>Visit ‘Settings > Shortcode in Comment’ to set what shortcodes are enabled in comments.</li>
<li>Type your shortcode(s) to be enabled in the text box (comma seperated for more than one)</li>
<li>Click ‘Save Changes’ to submit.</li>
</ol>

Shortcode in Comment

Enables blog owners to allow some shortcodes to be used in comments. You can choose what to allow.

godthor

This will create a new widget which will display your most popular posts and pages based on comment count with Disqus. Alternatively, you can use a shortcode as well.
It’s very simple to use. Just drag the widget into a sidebar and configure it, or visit the settings under the WordPress Settings menu.
Just Some of the Options:
<ul>
<li>Show featured image.</li>
<li>Choose featured image size.</li>
<li>Choose featured image alignment.</li>
<li>Show the post date.</li>
<li>Select how many days to check, IE: past 90 days.</li>
<li>Set how many posts to show.</li>
<li>Save the results for faster loading.</li>
<li>Load results using Ajax. Perfect to avoid caching results.</li>
</ul>
Note: This plugin requires you have an application registered with Disqus: https://disqus.com/api/applications/ 
It’s free and simple to setup, just follow that link.

Disqus Popular Posts

Creates a widget to show the most popular posts and pages on your site based on Disqus comments. Can also be used with a shortcode.

Shortcode in Comment vs Disqus Popular Posts