Unfortunately I think the author has passed away, but it would be interesting to see it rekindled and used for baseline comparisons like these.
- it is designed to be embedded directly in HTML
- it can listen for any event (unlike on* attributes)
- it has native support for CSS selectors: https://hyperscript.org/docs/#dom-literals
- it has async-transparency: https://hyperscript.org/docs/#async
- subjectively, it is easier to read than JavaScript, particularly for the short, light scripts it is designed for (toggling a class, etc.): `on click toggle .clicked on me`
hyperscript is more of a glue language than something I would recommend building an entire application out of (although people are doing that!)