I just like using Rust. This is a small side project of mine so it's been more fun to experiment with using Rust to make a backend api than to stick with rails.

I also recently dealt with maintaining / upgrading a large, not well architected rails app. Debugging mysterious issues in Rails (and asp.net webapi2) sucks compared to Rust.

For a professional project I would largely go with rails, depending on the situation. asp.net isn't bad either.