Darshan Sawardekar

<p>Adds a Scroll To Top button that allows visitors to scroll back to the<br />
top of the page. You can customize the button style using predefined<br />
styles or by adding a custom CSS file in your Theme.</p>
<h3>Credits</h3>
<ul>
<li>Thanks to <a href="http://markgoodyear.com/" rel="nofollow ugc">Mark Goodyear</a> for <a href="http://markgoodyear.com/2013/01/scrollup-jquery-plugin/" rel="nofollow ugc">scrollUp</a>.</li>
</ul>


wp-scroll-up

Adds a Button to Scroll back to Top of any Post or Page in WordPress.

Roman Sarvarov

<p>scrollToTop is a small plug-in that will help you to make a nice looking back to top button or full-height bar on your WordPress website. You don’t need any knowledge in HTML, CSS or JS: the plug-in has many settings which you can change in just one click.</p>
<h4>Features</h4>
<ul>
<li>Bar and Button mode</li>
<li>Choose 1 of 15+ arrow icons (which are merged in a font)</li>
<li>Change position, size, color, opacity and other styles</li>
<li>Enable/disable/change back to top text</li>
<li>Change animation effects (none/fade/slide)</li>
<li>Enable/disable async & defer script loading</li>
<li>Mobile friendly</li>
</ul>


scrollToTop

Create your own back to top button or full-height bar and simple customize it as you want.

wp-scroll-up vs scrollToTop