I'm not expert in Ruby, but I'd say there's definitely a few wins in typescript (types, performance, async). But the biggest wins have nothing to do with language differences, but rather not having to worry about that because you're using one language. If teams are large and split between api and frontend, then perhaps less of an issue. But if you're doing anything fullstack, to be able to use one language, everywhere with mostly the same ecosystem...well it's kind of what Java wanted to be.
And I say this coming from a python/django background. And ORM is one big thing that Rails/Django definitely are clear leaders in.
I like the one language thing. I think it's overrated a bit (most syntax mistakes I make are caught by linters) but it's nice.
However, it's still js. Lots of warts still. Also - for a normal web app I really don't see how async is a plus. I don't like promises or async that much, especially with so much db access - why would i want everything to go to an event loop?
It's a never ending discussion, I think all of these stacks are "good enough" to get the job done, a lot of it is how your brain ticks and what you're experienced with...
And I say this coming from a python/django background. And ORM is one big thing that Rails/Django definitely are clear leaders in.