As an Emacs lover, I soon found Org, and it was (and remains) the perfect tool, for working in plain text — which will never be obsolete, and works easily with git or version control. Then and now, nothing could match Org speed and flexibility: structural editing (creating nodes, moving nodes, promote/out-dent a node, demote/in-dent a node) was and is fundamental to Org (unlike Markdown etc), and it's ridiculously easy to reorganize thinking and writing as you go. You can export to LaTeX (or HTML) and customize formatting as needed, while also including code blocks from multiple languages. Integration with BibTeX was tight, and made handling hundreds of references easy.
Where other writing tools for complex documents previously made me cringe and cuss, Org makes writing a pure joy, freeing the mind to work entirely on content and its structure.