Regarding markdown, the recent release of Go introduces a simplified subset of Markdown for comments, which avoids a lot of complexity and inconsistencies of Markdown.

I want to add a WYSIWYG editor so that moronic scum users won't have to deal with any of this.

Users do not have to deal with any of this without a WYSIWYG editor. Users can just write in plain text.

Maybe neither BBCode nor Markdown is needed. HackerNews have only four formatting rule:

1. Blank lines separate paragraphs.
2. Text surrounded by asterisks is italicized (use \* or ** to escape).
3. Text after a blank line that is indented by two or more spaces is reproduced verbatim.
4. Urls (with or without surrounding angle brackets become links.

And it works well. I even think the second rule is unnecessary. Someone can use *word* or _word_ to emphasize something, but the website do not need to render them in italics or bold, or try to guess if they should be rendered in italics or bold (for example, 2 * 3 should be left as is).