CrestaProject

<a href="https://crestaproject.com/downloads/cresta-posts-box/" rel="nofollow ugc">Plugin Homepage & Demo</a>
With Cresta Posts Box you can show, in a single page (posts, pages or custom post types), a small box that allows the reader to go to the next or previous post. The box appears only when the reader finishes reading the current post.
Some features
<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>
PRO version features
<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.

kharim

WP Next Post Navi Plugin can easily add a Previous Post and Next Post link on your blog. You can choose to use buttons or text link.
This plugin gives you customization options to make the buttons blend in with your blog’s theme. So changed the color to match your blog or to make the buttons stand out.
Use custom text as well or choose to show the blog post title.
If you don’t want to use text links or buttons then you have the option to use images. Use your own images or use the ones that comes with the plugin.
When viewing the latest posts on your blog, there will be an option to show a message showing next post coming soon or you can disable it.
You can keep more traffic on your blog. This plugin will encourage your blog visitors to stay on your blog longer and continue reading more blog posts. (This will help to retain your blog visitors and in effect to reduce your bounce rate).
Responsive layout and very lightweight (no javascript).

WP Next Post Navi

WP Next Post Navi Plugin can easily add a Previous Post and Next Post link on your blog. You can choose to use buttons or text link.

Cresta Posts Box vs WP Next Post Navi