Shortcode

Shortcode is a module which integrates with WYSIWYG that adds tokens for embedding media and other content.

Fences

Fences is a great module to clean up your markup. A must know module! As the project page says, "Compare Drupal 7’s default markup for a field:"

CKEditor

CKEditor is new favorite rich text editor however I prefer to use the WYSIWYG module because it seems to have better media module support. This module, however, is needed if you plan to use the Scald module. If unsure, then I suggest using the WYSIWYG module instead.