What stack do you prefer these days?
It seems some folks still have their eye on the "full stack / single language" holy grail.
I'm still appalled by the state of many things in JS tbh. I have the impression you have to perpetually move your codebase by adapting to your stack underlying changes, may it be the build system, the framework, tools or libraries that deprecate themselves quickly...
The reasons that made start Opa are still there: There should be an easy single language to program web apps and a clean coherent single stack to build and run them.
Today, I mostly code in Go and I love it (single stack, tests built in) despite the lack of generics.
On the front-end, it's another story. If I have time one day, I'll rebuild something in that space.
JSX is the most significant contribution that React brought to front-end programming. Personally I don't always use React, but I use JSX quite often. It's intuitive in a way custom syntax (the dozens of) never will be.