The best replacement for disqus is livefyre.

The best alternatives to disqus are rated as following:
★★★★★  livefyre
★★★  jetpack
★★★  discourse
★★★  intensedebate
★★  intense debate
★★  moot
★★  google plus comments
★★  echo
★★  jetpack comments
★★  facebook comments
★  outbrain
★  squarespace comments
★  commentluv
★  wordpress comments

Your alternative for disqus is not listed? Suggest!
Speaking about disqus, one probably shouldn't forget about tumblr.

Other search terms related to disqus and their ratings are:
★★★★★ tumblr
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Google Trends

Scale is based on the average worldwide traffic of disqus in all years. Click on graph for more.
disqus
livefyre
jetpack