Tailwind CSS or Bulma CSS?

It's a bit of an apples and oranges comparison. Tailwind is a utility-first css toolkit which doesn't have pre-fabricated components. You can use one of the pre-built component libraries like TailwindUI, but Tailwind itself doesn't include these.

Bulma on the other hand is a more traditional CSS framework with an existing set of components you can build on. It's similar to Bootstrap, Semantic UI, Material UI, and many others. One notable thing about Bulma, aside from it's nice responsive design, is it doesn't force you to use any specific javascript library.

Traditional frameworks (e.g. Bulma) are great if you don't have lots of design experience but want to build something decent looking. You just grab the snippets you want and get rolling. You can customize things, but you'll need to learn their system.

Utility first is great if you know the design you want to build but don't want to deal with writing vanilla CSS. Tailwind can speed this up quite substantially.

I've used and like both, but since I care more about doing custom designs and build my own components I almost always go for Tailwind.

Tailwind, every time!