The main benefit of NextJS is that it makes it very easy to write code once and quickly swap whether it's going to be statically generated ahead of time, rendered on the server, or rendered dynamically on the client. It also comes with a bunch of features you'll likely need for a modern web page like image optimization and a really nice PaaS to deploy it to.

I'm not sure how extensible Hugo is, but Next allows full server side code. From my understanding (which may very well be wrong), Hugo is for static site generation.

Go's templating system is woefully awful.

If you want a fully static site, go with Hugo. Site generation is way way faster.

Next offers using React as your templating language as well as adding in server side code if you want instead of static site generation.

One benefit is that it's JS. Yes, really. For every Go developer, there are a thousand that know JS.