Rakib Hossain

The easiest to use rating option in comment! <a href="http://www.rakibhossain.cf/comment-rating" rel="nofollow ugc">Fa Comment Rating</a> plugin allows you to add a rating field in your comment from. Rating would be visible after comment content.
You can modify user comment rating by your dashboard comment screen.

Fa Comment Rating

Adds an awesome rating field in comment form.

Alex Alevy

This plugin installs all of Pivto’s social capabilities to your blog to transform it into an s-blog! With easy steps transform your blog into a social network (SNS) centered around your posts and user-generated content.
Among others, out of the box features include: 1. Social feed. 2. Social logins. 3. User profiles. 4. Comments. 5. Ratings. 6. Social network sharing buttons (e.g. like, tweet, etc). 7. Adding items to users’ collections (wish lists). 8. Connecting your company’s blog to your related social networking accounts (Twitter, Foursquare, etc). Show all your social activity integrated in your site.
For more information visit <a href="www.pivto.com" rel="nofollow ugc">www.pivto.com</a>.

Pivto for WordPress

Instantly transforms your blog into an s-blog! Change your classic blog or shopping site into a fun social networking site (SNS) around your posts and …

Fa Comment Rating vs Pivto for WordPress