I generally like modern React UI styling, particularly the more minimal ones like Shadcn. Material is solid, but too normie and played out for my taste.

They've evolved to their current forms through billions of user feedback loops, so it's hard to argue against survival of the fittest.

I also like some of the retro / minimalist UIs, but I doubt they have as much potential for mass appeal.

I think DHH did a great job with Omarchy. It's a fresh mashup of retro and modern UI aesthetics. I could see this catching on.