[skywritergr]

I used Katex on my GatsbyJS blog and it worked nicely. Felt like doing latex but less confusing.

[esperent]

If you already know latex pretty well then it's pretty confusing because you'll keep finding that things you expect to work are not supported.

[vcxy]

This is my experience as well. I just stick with MathJax for this reason. Since I'm already very familiar with LaTeX proper (use it every single work day), it's far less jarring to just use MathJax.