CrestaProject

<p><a href="https://crestaproject.com/downloads/cresta-posts-box/" rel="nofollow ugc">Plugin Homepage & Demo</a></p>
<p>With <strong>Cresta Posts Box</strong> you can show, in a single page (posts, pages or custom post types), a small box that allows the reader to <strong>go to the next or previous post</strong>. The box appears only when the reader finishes reading the current post.</p>
<p><strong>Some features</strong></p>
<ul>
<li>Choose to show next or previous post</li>
<li>Choose the box position (left or right)</li>
<li>Choose the font size</li>
<li>Choose the box width</li>
<li>and more…</li>
</ul>
<p><strong>PRO version features</strong></p>
<ul>
<li>Show Random Post</li>
<li>Show Related Post</li>
<li>Set box background color</li>
<li>Set box text and link color</li>
<li>Set border box and border radius box</li>
<li>5 Animations</li>
<li>and much more…</li>
</ul>


Cresta Posts Box

In free version, you have to chose to show only previous or next post. Too limited to be really useful.

Too poor in free version

Show the next or previous post in a box that appears when the user scrolls to the bottom of a current post.

Fantastic Plugins

<p>WP Post Navigator is a WordPress Plugin to Add Previous/Next Post Navigation Button. It works automatically once the Plugin is activated.</p>
<h4>WP Post Navigator Features</h4>
<ol>
<li>It works automatically when the Plugin is activated.</li>
<li>It has an option ON/OFF to disable the Previous/Next Buttons.</li>
<li>5 different types of Button styles to choose from Settings Page.</li>
<li>Should work in all major Browsers and WordPress themes.</li>
<li>Simple and Easy to set up.</li>
</ol>
<h4>Fantastic Plugins Official Page</h4>
<p>Join <a href="http://fantasticplugins.com/shop/free-member/" rel="dofollow nofollow ugc">Fantastic Plugins</a> to get a Free WordPress Plugins.</p>
<h4>Pro Version of WP Post Navigator</h4>
<p>Check out <a href="http://fantasticplugins.com/shop/awesome-previous-next-post-navigator/" rel="dofollow nofollow ugc">Awesome Previous Next Post Navigator</a> which has 200 Button Styles and Option to Add your Own Custom Button Styles.</p>
<h4>Support</h4>
<p><a href="http://fantasticplugins.com/my-account/" rel="nofollow ugc">Register here</a> and open a ticket for support.</p>


WP Post Navigator

Adds the Previous and Next Post Navigator Buttons on the left and right side of your WordPress Post.

Cresta Posts Box vs WP Post Navigator