Depends on the criteria, e.g. if dev speed has highest prio, a full blown component lib like Material UI would be superior to shadcn. CSS can obviously do things that tailwind can't, so it is more powerful.
The point of shadcn is you can pull in a component and modify it any way you want. It's always going to be bare bones at the start. Something like MUI locks you into a layout and style that's coupled with the API, and you need to rewrite big chunks of your app if you want to add your own branding.
For me the best middle ground is Headless UI or Bits for Svelte, unstyled and composable but you don't need to vendor code into your repo like shadcn.