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.

SwiftNinjaPro

Comments that Strip away HTML, but allow basic fonts in another way. Also includes some basic spam control options.
Comments will attempt to remove html and still allow users to add built-in non-html tags (made by the plugin) for bold, italic, ect. text.
The plugins built-in non-html tags will only run on the front end, which can help protect the backend from getting hijacked.
Plugin will include your old comments and use the same database.
Disables default wordpress comments on any page with the shortcode.
Plugin Includes Some Spam Control Options.
Comments can Optionally be made specific to a query var in the url, so one post can show comments specific to that query.
You can change the background, text, and button colors of comments to better match your theme.

Better Page Comments

Comments that Strip away HTML, but allow basic fonts in another way. Also includes some basic spam control options.

Shortcode in Comment vs Better Page Comments