SolijS is just JS without much magic. It's simple, small and very fast.

You can use signals and effects outside of components and it just works. You can even use a signal from the global scope within a component. Tracking of signals for effects and derived values is automatic. It looks very similar to React, but it's better in every way. Honestly the first time I'm happy with this kind of library. Don't need much more.

Edit: As for Svelte: like it too, but at least before Svelte 5 there were some footguns and differences between components and "normal" JS code. I haven't tried Svelte 5 yet, only watched some videos. From the looks of it would consider it as a good alternative.