WhizKins

WPSimpleInsert is a plugin to insert custom code in your blog posts. It includes options to either add the code above 
or below post content.
Features:
<ul>
<li>Add custom HTML/PHP/JavaScript to your posts.</li>
<li>Ability to add custom code above or below post content.</li>
<li>Options to hide the code from certain pages like the home page and category and archives pages.</li>
</ul>

WP Simple Insert

A plugin to insert custom HTML or PHP code in your posts. Includes options to insert before or after post content.

LuckyWP

The “LuckyWP Scripts Control” plugin allows you to insert and manage custom code into website. For example, you can insert Google Analytics code, Google Search Console verification meta tag, Facebook pixel, custom CSS/JS and other code without edit theme files.
<h4>Features</h4>
<ul>
<li>Great user interface: simple and functionally.</li>
<li>Insert code before <code></head></code>, after <code><body></code> or before <code></body></code>.</li>
<li>Items sortable.</li>
<li>Add Google Analytics code.</li>
<li>Add Google Verification meta tag.</li>
<li>Add Google Tag Manager code.</li>
<li>Add Facebook pixel code.</li>
<li>Add custom meta tags.</li>
<li>Add custom JS/CSS/HTML code.</li>
<li>RTL support.</li>
</ul>

LuckyWP Scripts Control

A great way to insert and manage custom code (CSS, JS, meta tags, etc.) into website before </head>, after <body> or before </body>.

WP Simple Insert vs LuckyWP Scripts Control