I don't have the Scala experience to compare the two, but I can say that Ruby is a wonderful language. For procedural programming where you don't need a lot of concurrent execution threads, it's superior to Node.JS in my opinion. All of the concepts from Typescript have equivalent syntax in Ruby, but there are fewer symbols (e.g. () => { ... }); ) and more keywords (eg 'do ... end'). It's a very flexible language and allows for a lot of different approaches to how it's written, so coding standards and careful organization is important. In the long run, however, you'll find it quicker to debug than Node.JS and just as powerful.

If you are comfortable with TypeScript, why not evolve to a C# ecosystem? Asp.Net Core + Entity Framework is a mature and well supported technology. As far as I can see in the enterprise market, the most adopted choice is still Java. So, maybe you may have a look to SpringBoot - and ultimately Quarkus.

This is advice regardless of your background and requirements. The Play framework has a terrible and complicated design, don't risk it. I even suggest Spring and Kotlin over it! You can use Scala for small services and Data Engineering stuff and benefit optimizations and threading of JVM. RoR, on the other hand, has a huge development speed, which I believe is a big advantage cause you can handle performance bottlenecks later. Also, Scala has another downside, which is featureful in terms of OO and FP paradigms, which makes anyone write code freely with any personal style and makes it a problem in a team, Hence a coding style has to be defined if there would be Scala development team.

If software performance is your top priority, then Scala/Play is probably best. If developer productivity is your top priority, then Ruby on Rails is the best choice in my opinion.

The Rails framework is batteries-included. The framework takes care of many things by default so that you don't have to. Logging, security, etc. It's also well-integrated; for example, controllers understand models out of the box. I had a better experience with RoR than with Play.

On the other hand, Scala and the JVM are more performant in general, so they can scale to serve more requests per second on the same hardware.

If you're considering serverless functions, then Scala is probably a better choice because it would be faster to load, giving you better economics.