There are tons that look visually appealing, but very few I've found that take a component-based approach (where they document each component individually - or think about how they interplay with each other). I've found the CSS is usually muddled, they often have legacy build pipelines that has to be rewritten to fit with Webpack, and a distinct lack of flexibility.

If Adam solves that side, Tailwind UI will be worth the money.

If it causes other theme providers to up their game, even better.