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.

mrpaolo

If you have ever asked yourselves:
<ul>
<li>How many articles per month are published on my website? And how many comments?</li>
<li>Which is the longest articles published on my site? And the shortest?</li>
<li>Which are the most commented posts of the year?</li>
<li>How many words are in total in your post? And on average?</li>
</ul>
Well, then with SiteStats you get all those answers (and much more!) in one place with a beautiful interface.

SiteStats

Provides useful and interesting statistics about your Wordpress website.

Category Popular Tags vs SiteStats