Georgi Popov

This plugin provides a list of similar / related entries to an article or a custom post type entry.
This list could be added in the form of a:
<ol>
<li>Gutenberg Block</li>
<li>Shortcode</li>
<li>Widget</li>
</ol>
If you add a widget to the sidebar it will only appear when on the details view of an entry, as similarity cannot be calculated when on a list page of multiple entries.
The syntax for the shortcode is <code>[magadanski-similar-posts id="" post_type="" taxonomy="" limit=""]</code>
You can use the attributes as follows:
<ol>
<li>ID — (integer) the ID of the post you’d like to get similar posts for. Default value: the current post ID.</li>
<li>post_type — (string) the post type you’d like to query. Default value: “post”.</li>
<li>taxonomy — (string) the taxonomy based on which you’d like to get similar items. Default value: “category”.</li>
<li>limit — (integer) a maximum number of results you’d like to receive. Default value: 5.</li>
</ol>
The similarity is considered based on the number of common categories (or other taxonomy terms) for this post and the rest of the posts in your blog.

M Similar Posts

This plugin lists similar to the current post based on the number of common categories.

Recmnd allows you to show related content to your readers. The recommendations are real-time and change when you update your content or when you publish new articles. All recommendations are served via a widget and you control its style, the information shown for each suggestion, the number of displayed recommendations, the time period of the recommendations, and the depth of the recommendation analysis. In order to use the Recmnd service you must register for an account: <a href="http://www.recmnd.com/plans/" rel="nofollow ugc">http://www.recmnd.com/plans/</a>. This plugin works with our trial accounts as well.
For more information, please visit the Recmnd website at <a href="http://www.recmnd.com/" rel="nofollow ugc">http://www.recmnd.com/</a>.

Recmnd

The plugin allows you to use the Recmnd service (www.recmnd.com - automatic recommendations) with your WordPress blog without coding.

M Similar Posts vs Recmnd