Ask them how they’ve addressed SEO. I doubt there’s a good answer. In my experience you’re better off just using Wordpress for a marketing website. It already does the vast majority of what a marketing website needs. Now, a rich web portal/SaaS product is a different story. Choosing the right tool for the job only comes with experience.

You could suggest them to use React/NextJS, but publish a static export (yarn export) which is the buildtime compiled HTML+CSS+JS from react, but without needing anything else.

Works well for static pages, this is what I did so II could use next/react and deploy to a boring LAMP server we have for our landing pages.

Don’t do this. I’ve just been through the process. Trust me. For a marketing website just use Wordpress and save your time for something more valuable.

It works for me, already shipped. A bit late for the advice I guess. Use what you know?

Works for me too -- for me, Gatsby or Hugo etc are quicker and simpler than WP

Especially long term wrt security