JSX does seem to fit that niche better than any other alternative I've tried. It pulls off a rather remarkable trick of avoiding the "uncanny valley" that you usually get from starting with a language and contorting it to do something different.

JSX manages to feel just about right: it's plain-old-HTML when you want it to be, and plain-old-Javascript when you need an out.

Still... I wouldn't mind writing in a truly standard language. You're "really" writing the DOM, and HTML and DOM are this godawful bastardization of a user-interface description language. I'd be slightly less grumpy to have a good DOM-writing library, and deal with its ugliness, rather than mix-and-match the domain-specific-language in with my actual coding language.

I'd written myself a good Java version of this type of thing, and I found it kinda pleasant -- especially since it let me do HTML structure checking via the Java type checking. Typescript is -- God help me -- actually a pretty good language, and I'd be OK with actually writing my user interface structure in it, with the help of a good library.

At least then I'm writing in only one language. That saves me time to go out and learn the godawful bodge of CSS to make it look pretty.