Abidemi Kusimo

You can make use of category popular tag to display most used tag on your blog. This will give list of frequently used tag anywhere you place the shortcode or funtion in your theme.
For example [popular_category_tags count=10 type=”popular-tags” category_id=”1″]. 
You can also call this function from your theme file: cush_category_popular_tag() for basic output.
When using the shortcode type is required. category id, count is not required. if no category id suplied, the plugin will default to current post category available. 
For example [popular_category_tags type=”popular-tags” ].
You can find category tags options under Settings page 
Settings -> Category Tags
Credit : (https://wordpress.stackexchange.com/questions/261617/display-most-popular-tags-of-category)

Category Popular Tags

Display popular tags on achieve/category page of your theme using sortcode or by calling a function.

RobMarsh

Popular Posts displays a list of your blog’s most-viewed posts. The output can be customised in <a href="http://rmarsh.com/plugins/post-options/" rel="nofollow ugc">many</a> ways.
This plugin requires the latest version of the Post-Plugin Library: <a href="https://downloads.wordpress.org/plugin/post-plugin-library.zip" rel="nofollow ugc">download it now</a>.
<h3>Version History</h3>
<ul>
<li>2.6.2.0
<ul>
<li>first release — numbered to match family of post-plugins</li>
</ul>
</li>
</ul>

Category Popular Tags vs Popular Posts