Some personal news, I migrated this site to Next.js. I chose Gatsby in the past because its static generation features. Next.js only had a partial support for static generation because it heavily focused on SSR at that time.
But I've been using Next.js with my recent side projects and my experience has been great. There is no almost any difference from the performance perspective, but the DX is way better for me in Next. Also, I read a lot of comments about the (shitty) culture in Gatsby, and honestly, it's something that bothered me. So I decided to make the move.
I'm not going to detail the migration steps, because you have the official documentation from Vercel, but I took a day to move all the things, it went smooth.