Mithril is a modern JavaScript framework for creating interactive single page applications. It provides rich features such as routing, component-based views, and a Virtual DOM, making it easy to create dynamic, responsive user interfaces. Mithril is lightweight and fast, with a minimal API surface area, making it easy to understand and develop applications with. It is open source and well-maintained, with a strong community of developers and users. Mithril is well-suited for both small and large applications, and provides a great development experience with minimal setup.
For now, I think Aurelia has the cleanest syntax.