I like the support in the community of Express.js.

Its lemma DRY - Don't repeat yourself promotes not writing twice the same code but using mechanisms and tools provided by Ruby and its framework Rails. Besides the way to create backend and frontend (now with Stimulus) is very clear, concise and standard. This leads to short code that is easy to understand, to debug and to correct. For the errors I have had with the framework I have opened issued in github and several people have jumped to solve.

Simple and easy development and deployment. Huge community and core development team. A large number of open-source projects to build literally anything out there.