Although WordPress is a content management system (CMS) for creating web pages, it cannot be classified as a web framework. If you're looking for a complete framework, I would suggest F.A.R.M (FastAPI, React JS, MongoDB) instead. I have personally utilized this stack to create our DevDash demo at Cisco Live and it has performed exceptionally well. Below is a high-level overview of the FARM stack's architecture.
@npetrele's post did remind me of this meme (and it is a Meme Monday) so I'll start off with this:
I know there are a few other factors to bring into the equation when thinking of what frameworks to use, but pretending it's a blank slate that I can decide completely solo, I actually would like to try out Express.js for the backend and then React as the frontend. To @davidn#'s point above, React is also not really a framework but a frontend library. So, if I had to go with an actual framework, it would end up being Vue.js. I've used Vue before but I haven't used Express before (although I've heard some great things about it).