Derek Ashauer

TinyMCE has a built in feature to include a predefined list of links to select from. This plugin simply creates a list 
from your pages in WordPress. Create a link like usual in TinyMCE, but you now have a new drop down menu called “Link List” 
where all pages/links are already setup for you.
This currently only works for pages, not for posts.

AWS Easy Page Link

Using the External Link List feature of TinyMCE, this makes it easy to create a link to another page on your website.

Steve Grunwell

<a href="https://codex.wordpress.org/Excerpt" rel="nofollow ugc">WordPress post excerpts</a> can be a great way to hand-craft the summary of your content. Unfortunately, writing post excerpts isn’t as nice of an experience as what you find elsewhere in WordPress. Want to include links in your excerpts, or bold some text? Hopefully you know some HTML!
Advanced Post Excerpts is designed to change that, by giving your editors an easy, intuitive interface for writing great post excerpts.
For complete details and/or to contribute to ongoing development, please <a href="https://github.com/stevegrunwell/advanced-post-excerpt" rel="nofollow ugc">visit this project on GitHub</a>.

Advanced Post Excerpt

Replace the default Post Excerpt meta box with a superior editing experience.

AWS Easy Page Link vs Advanced Post Excerpt