I've worked with Rails, I've worked with Phoenix, I've also built with Rust and Svelte. I'd choose Rust+Svelte every time. Much better experience. Rust's async is not nearly as bad as people make it out to be.

Building new Rails apps is a blast, but dealing with old Rails apps is a pain, they're difficult to refactor. New Rust apps are great, and dealing with old Rust apps is a much better experience as they're easier to refactor.