Sorry for the delayed reply, my phone died when I first tried to reply and it took me a few minutes to retype

Markdown -

Basically what's used on reddit. Also when you see a readme.md file on GitHub or whatever the .md means it's in markdown format. It's used in a bunch of places, you might already know how to use it.

Very simple in its core version. Other versions can add and remove parts but most versions are cross compatible with the famous version from reddit for ease of use.

No words used as formatting, only non-letter symbols like brackets and stuff. It doesn't care what languages you do or don't know, it's only biased on favor of people whose keyboards can easily access symbols like a parentheses or an exclamation point.

Wikitext -

Used on Wikipedia's MediaWiki software which is also the basis of others like the "fandom wiki."

Complex and feature-rich in its core version, with sidebars and tables and stuff like that, plus other versions being able to add more features. The Wikipedia version isn't usually cross-compatible with others because it has so many extensions, but it's one-way compatible where the core version can always be copied and pasted because you can only add functionality to the core version, not remove any from it. Even some articles on Wikipedia are simple enough to not use any extensions and be compatible both directions.

It does use words and abbreviations of words as part of its formatting. This means implementations must either support translated versions of the standard itself in all of the thousands of languages on earth, or at least the most used ones, or be flagrantly biased in making the standard easier to learn and use for people who use English.

Asciidoc -

I don't know what the hell is going on. It's complicated and has sidebars in its core version and it's extensible and language-centric like wikitext, but it's not wikitext. People already know how to use parts of it but I don't know anywhere it's been used. It's coming for me and it has a knife.