Typora with gotham theme - it is markdown, though, but has the ability to link files like [[wikilinks]] do. Marktext is rather ugly, but used to be far more powerful than Typora and was a Typora knock-off, but this last version I downloaded has too many glitches. ghostwriter with the dark colorful theme is good, too and, when in preview mode, you can also open internal links to your other files. If you write a lot, it is well worth your time to learn markdown and use its editors - but only if they have the interacting outline pane. Vim and Emacs take forever to learn. I can use markdown, though, in email (if I use a browser extension) or online on Nextcloud's page or on some phone apps. If you find a favorite, try to customize a css file a bit to make it your own and back up that css file. With a markdown editor, you can read those files on almost any other software, so are not tied down. Flexible and easy is great. Many regular editors like Atom and gedit have plugins/addons to give you at least some markdown functionality. The size of your files will be far tinier than an .rtf. .docx, or .odt file, but can still compress well. Many markdown editors can use or read highlighting,too, and of course you'll have bold. You can write quotes and code blocks and you can also use a lot of markdown on social media (even on Lemmy) and it helps with html.