I will not explain the long story why it is better than others rather I would give you short points why I love it:
1. It is an addiction. I have been a regular commenter on Propakistani since 2013, and the main reason was Disqus.It acts like a social media when you comment and someone replies you, you get a notification in red light. Even you visit another website that uses Disqus, the red notification light is showed, and you go to the site to reply the person..
See Screenhot: https://goo.gl/9bJ66j
2. It is easy to implement. On Bloggers, it takes just one 1 minute, on WordPress, it may 2 to 3 minutes.
3. Users can sign in with email, Facebook, Twitter and Google.
4. You can place any PNG to the avatar of your users.
5. It shows Admin or Moderator Sign on the admin account, the same way it is being shown to my ID in BloggersFunda.
6. Users stay on your site longer time, so it reduces the bounce rate and according to SEMRUSH latest Ranking Factors, it ranks a site higher. See at https://www.semrush.com/ranking-factors/
7. It looks professional as compared to other comment system.
8. It increases Pageviews because it shows related artiecles below the comments and the comment of other users. People love to see the comments of other people so it incresaes pageviews.
9. It has great reply system, you can see all comments in one place. You can see the email, IP Address, and you can block a user.
If you want to know how to install:
On Google: How to Install Disqus on WordPress (or Blogger) If you need a video, type the same on Youtube.
All these 10 points are according to my experience, it may have other advantages as well.
What do you say about it? Feedbacks are welcomed!