When is Next.js better than Gatsby?
They can both help with server-side rendering, but in 2 different ways.
The end result using Gatsby is a static site generator, without a server. You build the site, and then you deploy the result of the build process statically on Netlify or another static hosting site.
Next.js provides a backend that can server side render a response to request, allowing you to create a dynamic website, which means you will deploy it on a platform that can run Node.js.
Next.js can generate a static site too, but I would not say it’s its main use case.
If my goal was to build a static site, I’d have a hard time choosing and perhaps Gatsby has a better ecosystem of plugins, including many for blogging in particular.
Gatsby is also heavily based on GraphQL, something you might really like or dislike depending on your opinions and needs.
Here's my latest YouTube video. I talk about why I think that dogs are a great help for developers working remotely: