Pandoc if you like markdown -- it allows LaTeX math and equations. Emacs org mode if you like emacs and not markdown.<p>Lately I&#x27;ve just found it easiest to use a text editor that has good keyboard support for entering unicode and just type everything in plain text. Vim&#x27;s digraphs or Emacs&#x27;s TeX input method are what I have in mind. It works fine for most personal notes (with a few unevaluated LaTeX macros on occasion) and it&#x27;s not hard to go back later and convert it into a pandoc markdown document for nicer formatting.