But they're both framework-agnostic.

This snippet works with any framework and any build step.

  <script src="https://unpkg.com/alpinejs@3.x.x/dist/cdn.min.js" defer></script>
  <div x-data="{ 
    today: new Date().toDateString(),
    randomNum: Math.floor(Math.random() \* 100)
  }">
    <p>Today is <span x-text="today"></span></p>
    <p>Random number: <span x-text="randomNum"></span></p>
  </div>

I'll concede that Alpine.js is harder to understand and more verbose than Marko's syntax, but in order to use Marko you have to commit to the Marko framework. If you're willing to choose a framework solely for its JS-in-HTML capabilities, there are much better choices (like SvelteKit that handles JS-in-HTML wonderfully).