@smitten shadcn-ui is my go-to now (though it's not quite a component library)! It is mostly built on top of radix-ui which is already a very good headless component library, but also with very well-designed default stylings so I don't have to do as much work customizing, and the copy-paste approach is really good at allowing me to truly own the components when I do need to customize. It has a pretty nice CLI too!
https://ui.shadcn.com/