When Blogger asked for suggestions, the top most suggestion was that there is need for improvement in the default commenting system. While Blogger is trying to implement these suggestions, those who cannot wait and are really looking for good alternative commenting systems for blogger, then you’re at the right place. Blogger’s default commenting system lacks basic features like spam filtering, threading and gravatar support which is found in many other commenting systems.
I will be comparing 3 kickass commenting systems which you can use for blogger.

Js-Kit
Features

  • Spam control with Akismet
  • Banning : Ban a person by the user name or by IP address
  • Gravatar Support
  • TrackBack/PingBack: Trackbacks/Pingbacks can be automatically be included in comments.
  • Comment Ratings and Karma: Users can rate comments.
  • Blogger Comment Sync: (Best Feature) Transparently switch back and forth between native Blogger comment system and JS-Kit Comment system with no loss of comments because comments are always synchronized with Blogger.
  • Emoticons: 16 emoticons are available.
  • Threads: Threading is also available
  • Pagination: Comments can be paged.
  • Commentluv a feature to give love to your commenter is available to only this commenting system
  • Photo as well as video comments.

Intense DebateFeatures:

  • Comment Threading
  • Reply By Email: Respond to and moderate comments with ease via email
  • Commenter Profiles: Special Profiles for commenters so that there is more interaction between people.
  • Moderation/Blacklisting
  • Reputation Points & Comment Voting
  • Twitter: Tweet your comments
  • Widgets: widgets like blog’s comment stats, the most recent comments made on blog, most popular posts and the most recent comment
  • FriendFeed:(Best Feature)When comments are made in the context of a blog on FriendFeed, IntenseDebate will republish them back on the blog.
  • Plugins API:Developers can enhance the comments by plugins like Seesmic video comments, PollDaddy polls, YouTube videos, smileys.
  • Gravatar support.
  • Facebook Connect and Twitter Sign-in: People comment via their facebook and twitter profiles and can further broadcast the content.

Disqus
Features

  • Social Media Reactions: (Best Feature) Display mentions and comments about post from other services around the web (e.g. Twitter, FriendFeed, Digg, YouTube).
  • Trackbacks
  • Seesmic Video Comments
  • Pagination
  • Threading
  • Facebook Connect and Twitter Sign-in: People comment via their facebook and twitter profiles and can further broadcast the content.
  • Widgets like Popular posts and top commenter’s widgets.
  • Blacklisting as well as whitelisting people.

Among the three commenting systems, Js-Kit is the easiest to install, whereas
Disqus and Intense Debate are feature rich.
Js-Kit is best for people who want the option of reverting back to blogger.
But above all they are much better in comparison to the blogger’s default commenting system.