SEO: One product page with multiple options VS multiple product pages with single option

Hello,

What do you think is best for the overall ranking of the website on search engine?

- One product page with multiple options (e.g. I sell one T-shirt with 100 different designs = 1 product page)
Or
- One Hundred product pages with one option (e.g. I sell 100 different T-shirts = 100 product pages)

I can write one long description for the first case or 100 unique description for each products in the second case.

T-shirts are only an example here. For my actual products, either ways are fine regarding the customer experience. My question is only about the SEO impact for my website.

Which way would you choose for a better ranking on google?

check the top 5 of the SERP and see what others are doing
your content format needs to match theirs to rank, otherwise you will have a hard time

Thanks! What if half of them are doing one way and the other half doing the other way?