[grayclhn]

Pandoc if you like markdown -- it allows LaTeX math and equations. Emacs org mode if you like emacs and not markdown.

Lately I'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's digraphs or Emacs'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's not hard to go back later and convert it into a pandoc markdown document for nicer formatting.

[cben]

Yep. For notes there is little justification for the full complexity of LaTeX, the most one needs is islands of LaTeX math. And you don't even need TeX installed — html with mathjax/katex is more flexible most of the time (but Pandoc will easily convert to latex/beamer when you need them).

I'm cataloguing math support in markdown tools at https://github.com/cben/mathdown/wiki/math-in-markdown (help welcome). If you don't know where to start, the first to check out are probably StackEdit, Atom + https://discuss.atom.io/t/using-atom-for-academic-writing/19....

I have a theory that a single pane styled in-place is nicer for quick writing than 2 source+preview pane. Typora, Texts.io, and my own https://mathdown.net do that.

If you do want full latex, try Overleaf.com, which has "rich text" mode where many constructs (sections, lists, math) are styled in-place (you could even hide the PDF pane).