Kishores

Post Featured Icon: It allows to add font icons to post title, and there is option so that we can 
replace post thumbnail with font icon.
It supports:
<ul>
<li>dashicons</li>
<li>genericons</li>
<li>font-awesome</li>
</ul>
Please check here: <a href="http://opentuteplus.com/post-featured-font-icon/" rel="nofollow ugc">Demo 1</a> and <a href="http://blog.kishorechandra.co.in/project-fork-in-open-source/" rel="nofollow ugc">Demo 2</a>
It supports post,page.But we can add to custom post types to. It provides hooks i.e icon_post_type .
<blockquote>
Priority Support
If you are looking for more features, paid support or Custom WordPress Work, then you can hire me too. My email id : babunsahoo@gmail.com .
</blockquote>
<pre><code>// Our filter callback function
function icon_post_type_callback( $types ) {
 $types = array('post', 'page', 'product');
 return $types;
}
add_filter( 'icon_post_type', 'icon_post_type_callback', 10, 1 );
</code></pre>

Post Featured Font Icon

it supports dashicons, genericons, font-awesome.

keyra

This plugin disables genericons css in twentyfourteen, twentyfifteen or twentysixteen (it may be compatible with other themes).

Disable Genericons

This plugin disables genericons css in twentyfourteen, twentyfifteen or twentysixteen (it may be compatible with other themes).

Post Featured Font Icon vs Disable Genericons