Ask HN: Good AI tool for UI mockups without code?

What tool have you found to be useful to generate screens/components for an app? Basically a UX design tool rather than a dev tool.

The problem with most code generation tools is that they're limited by their ability to provide working code. ie., there could be a great screen concept, but the visualisation doesn't reach me (the user) because it just isn't able to generate code for it.

What I want is for it to focus on the best UX design and just spit out images so I can then go about with development.