I've recently been pretty busy writing posts on a satirical character blog. The site is built using Yola which is just fantastic. The only downside to Yola blogs is that they don't come with a comment system installed already. They have partnered with Disqus, however.
There are instructions for how to install this comment system on Yola, but people seem to have a lot of trouble with it for some reason. Google the subject and you'll see some queries on the Yola help forum.
I had some issues myself. I thought I was doing everything exactly as described. But it turned out that the the window that contains the code you're supposed to put into your Yola site was quite narrow, and only showed the first two lines. I cut and pasted that alone and of course it didn't work.
It was only when I scrolled down through the actual window that I saw all the code I was missing. Of course when I used that, it all worked fine. So, if you are trying to install the code into Yola (or another platform) then keep an eye out for this problem.
Disqus is a really good system, by the way. What I like about it is that you can do a lot of customization, including listing social media references to your blog posts. A lot of the pre-installed comment systems don't have that facility.
Another one like Disqus that is worth considering is IntenseDebate.