I must add Asciidoctor. Which is mostly compatible with Asciidoc, but even more powerful.

I have spent a lot of time trying to make Asciidoc create beautiful PDFs for technical documentation, but Asciidoctor makes it all a lot easier to customize its own stylesheets.

The only negative thing about it is that it is hard to install since it typically isn't found in your distros package repo by default.

I agree. For me, Asciidoc hits the sweet spot as it seems to have much of the simplicity of Markdown, and with the AsciiDoctor/DocBook toolchain it has the publishing power of RestructuredText.

But its tables beat both hands down. You can include a csv file with some headers or micromanage merged cells, alignment and such.

I was in attendance for a conference presentation a few years back that O'Rielly was moving to writing books in an asciidoc editor which would be converted to (x)html5 for easy conversion to PDF and ePUB.

I wonder if that thing ever took off. Previously, it was said, that they were working in docbook (XML)

I would also add that Asciidoctor has the best extension experience out there. It has named blocks and inline sequences that can be handled correctly by a plugin, which is amazing if you ever tried to add syntax into Markdown. Just compare how bug-free and simple is embedding Mathjax into Asciidoctor compared to Markdown: last time I've checked you had to manually process Markdown to extract all Mathjax stuff, apply Markdown and then inject Mathjax back. With Asciidoctor it's a no-brainer.

Edit: it's also available in Ruby, JS and on JVM!

I looked into these recently and found AsciiDoc the most promising for lightweight technical documentation, but I'm still having a very hard time getting myself to use it instead of Markdown.

AsciiDoc has some very newbie-hostile quirks, at least as of now it more or less requires asciidoctor, and even then its output HTML is terrible. Terrible as in Wrong, as in...

    <div class="paragraph"><p>Oh no...</p></div>

In fact, since I have not yet found an asciidoc converter that produces decent HTML, and I don't have time to write one, I may yet fall back into the "everything sorta supports Markdown" trap.

Indeed. We recently started a large rewrite of our product's Developer's Guide which was previously written in DocBook. All the writers are quite happy about Asciidoc and it took us only a few days of work to recreate custom additions we added to DocBook.

That being said, while the user documentation is (mostly) excellent, the developer documentation is abysmal to non-existent. On the positive side, though, the developers are quite active and responsive on Github. But if you're only writing documents instead of extending the language with new macros, you won't notice anything of that.

Asciidoc is really underrated. It feels more "natural" than RST and scales up to large documents. I wish people spent more time looking at alternatives instead of jumping on bandwagons.