We installed several wordpress related posts plugins and we compared them.
Jetpack plugin
The

By default, jetpack adds a nofollow to internal links!!! That was it about Jetpack.
YARRP
Yarrp is pretty popular among wordpress webmasters. It displays related posts nicely. However, I have spotted that the displayed posts were often not accurate. In fact, for some reasons, one post always showed up even if this post wasn’t important at all. For now, in 2018, Yarrp is not compatible with Gutenberg. Leave a comment if it is compatible someday.
Contextual Related posts
This is the plugin we use. This is the best because it shows the most accurate related posts. It helps the google juice flow through the whole website. However, the style of the related posts, old fashion squared thumbnail with the title highlight in front of the thumbnails, aren’t appealing. Nevertheless, you can code the CSS of the related posts to make it look good.
Yuzo related posts plugin
If you don’t like to code CSS, download the Yuzo related posts plugin since it looks good on every theme. At last the related posts look better than with CRP or YARRP. Nevertheless, the choice of related posts isn’t as good as CRP. Nevertheless, with Yuzo, you can choose which related posts should appear on every page and it is golden.