I hope this question is not deemed off-topic, but I cannot think of a more appropriate place to ask it (few tech sites care about support for MathJax and $\LaTeX$), and I think that blogging about mathematical topics is certainly part of mathematical education viewed in the broad sense.
Anyway, I currently have an almost-dormant blog on wordpress.com, and I would like to reinvigorate it and post more frequently. However I have realised that Wordpress itself is hampering me, largely because of its primitive support for $\LaTeX$; every expression has to be between non-standard delimiters and is then replaced by an image which is usually the wrong size and aligned incorrectly. So this results in tediously writing not-very-reusable source-text that is rendered into ugly output - basically a lose-lose-lose situation.
So really I need to use something that produces MathJax, and in addition it would be better if I could write once and render to either HTML or $\LaTeX$, which seems to limit the field to various Markdown editors. The StackEdit online editor is extremely good, produces output containing MathJax tags, and has a mechanism for direct "Publish to Wordpress". Almost perfect, except that it doesn't work properly for $\TeX$ - it just passes through the marked-up MathJax constructs which don't work on Wordpress. (It would work on a self-hosted Wordpress, where you can add your own Javascript, but my life is too short to get back into self-hosting.)
Anyway, I had better finish with an actual question:
What is the best way to write mathematical content, preferably using Markdown for formatting, and have the resulting content appear online, with the mathematics rendered in MathJax?