You can try any of the following
- tinymce ( https://www.tinymce.com/ )
- simplemde ( https://simplemde.com/ )
- trumbowyg ( https://alex-d.github.io/Trumbowyg/ )
I am currently using Trumbowygfor this discussion board, I was using TinyMCE before now, anyone you choose will be fine and they are both easy to configure. I don't think paid ones are better it will depend on what specific feature you need or maybe they offer support for paid ones.
Someone I know said Trix (https://trix-editor.org/) was also very good, I am yet to give a try.
Are the paid ones much better? Any recommendations for these?
Which one do you use for this discussion board?