Just talked on a slack about this. I strongly dislike htmx since it creates a DSL where there wasn't one needed. I think in general if you don't need to build custom behavior (which a SPA enables) then going pure SSR (without any of these) is a good way. If you need custom behavior then these solutions probably won't be enough. To me it feels like a very small slice that needs these solutions but still don't need a "more full JS frontend".

An example of the DSL in htmx I mentioned (from https://htmx.org/docs/#validation):

    <form hx-post="/test">
      <input _="on htmx:validation:validate
                  if my.value != 'foo'
                      call me.setCustomValidity('Please enter the value foo')
                  else
                      call me.setCustomValidity('')"
            name="example">
    </form>

To me this reinvents a subset of js (and compiles it down to js), event handlers, etc. If you just need some inline behavior just use the on* attributes that are in html and if you need more then write a js file and if you need even more use a framework.