Nextjs is most likely going to be the new Ruby on Rails. javascript all the way down, static rendering, PWA, server side rendering...everything baked in. This is a big backing for Next. However rebranding to Vercel is bad.
I prefer to use other languages on backend something like C#, because JavaScript is too error-prone. You can't even just add two numbers (try (0.1 + 0.2) === 0.3) without some workarounds. and there are millions other issues with the language.
Because I was curious, I tested it out with C# on repl.it and behold, 0.1 + 0.2 == 0.3 returns false in C# as well: https://repl.it/repls/AdoredValidVirtualmachines. Not very surprising of course, since that "error" is a result of the IEEE floating point spec and not of any language.