Typst is trying to take on LaTeX: high-quality PDF output, equation typesetting, citation and reference systems, programmability, etc.
But if you look closer, the actual syntax of Typst is clearly a mix of MarkDown and AsciiDoc (e.g. code blocks and lists work like MarkDown, while headers work like AsciiDoc, and I think the math syntax is to some degree inspired by AsciiMath from the AsciiDoc ecosystem).
As someone who mainly uses MarkDown to author PDFs, I find Typst to be a clear competitor to Markdown/AsciiDoc/Org as well as TeX. I think they're working on basic Typst support for Pandoc, in which case you might soon be able to generate HTML with it too.
The king in this space is Pandoc. It supports most things you might need in "serious" documents: figures, tables, equations, references, citations, etc. You can even customize the TeX export template if you need more control over the output. And if you need to later, you can easily re-export the same document to TeX, DOCX, or HTML.
Lately, I've also been using Quarto a bit. The default export is HTML but it also supports PDF. It's nice if you're into "literate programming", where you write code blocks (e.g. Python snippets) in a MarkDown file, and those code blocks are automatically used to generate figures, tables, etc. in your MarkDown file on export.
If you want something that "just works" and are not averse to commercial apps, I can recommend giving "iA Writer" a shot. It has a built-in preview and export solution that is lightning fast and has good support for equations. But I wouldn't use its export for anything important, as the output is clearly draft quality, and the MarkDown support lacks features like citations. (Though it supports footnotes, so for informal documents you can abuse that for citations.)
But if you look closer, the actual syntax of Typst is clearly a mix of MarkDown and AsciiDoc (e.g. code blocks and lists work like MarkDown, while headers work like AsciiDoc, and I think the math syntax is to some degree inspired by AsciiMath from the AsciiDoc ecosystem).
As someone who mainly uses MarkDown to author PDFs, I find Typst to be a clear competitor to Markdown/AsciiDoc/Org as well as TeX. I think they're working on basic Typst support for Pandoc, in which case you might soon be able to generate HTML with it too.