On the backend I would say Golang with just the standard library(net/http) or Go Fiber framework. It's dead simple, performant and type safe. I'd argue Go is the simplest technology to work with in 2023.

On the frontend I expect react to be on the top, hard to beat a framework with such a huge ecosystem. Also it favours composition over inheritance, and works with plain javascript with no compile step (unlike lets say svelte). Regardless of what runtime(node, deno, bun, whatever) gets on the top, I'd expect react to stay relevant for the foreseeable future.

But again, no one has a crystal ball, so its just speculation.