Some time after that I learned about Svelte and very quickly concluded that this would be my choice, everything just feels right about it. For the record, I've only done a small project in Svelte.
I can tell you that Hyperapp is not for everyone. If you want to write pure, immutable, functional JavaScript and think hard about client side app architecture (unidirectional state management, controlled side effects, toggleable subscriptions), then you'll love it.
If you are looking for a more accommodating, meet-in-the-middle kind of approach where you can mix programming styles, and don't want to think much about those things I mentioned above, then React, Vue, Svelte are all great choices.
V2 will be released in a few months, so do circle back to Hyperapp then to see how you like it again.
Definitely not planning to remove the current state or anything haha.
Maybe the person that said Svelte was more declarative was only familiar with an older incarnation of Hyperapp that wasn't completely based on functional principles, or maybe they're using a more loose but inaccurate definition of declarative (kind of like how people often say "theory" when they actually mean "hypothesis").