I've never used Rails, but I agree upon "the state of the modern landscape". Instead of looking backwards, I tried to look forward, and what I found was Elixir and the Phoenix framework.
You're about the 5th person now in as many days who has recommended Elixir when I mentioned I was building a project in Ruby. I'll definitely have to check it out for my next project (whatever that may be!) Can you expand on why you found it so appealing or "holy crap, this is awesome" things I should look at first ?
Elixir is a functional programming language based on the "BEAM", the Erlang VM. We'll get back to the BEAM in a moment, but first: the functional programming aspect. That definitely took getting used to. I remember being _very_ confused in the first few weeks. Not because of the syntax (Elixir is quite Ruby-esque) but because of the "flow" of code.
However, when it clicked, it was immediately clear how easy it becomes to write elegant and maintainable code. There is no global state in Elixir, and using macros for meta-programming are generally not encouraged. That means it becomes very easy to reason about a module/function: some data comes in, a function does something with that data, and some data comes out. If you need to do more things to the data, then you chain multiple functions in a "pipe", just like how you chain multiple bash tools on the command line.
The Phoenix framework applies this concept to the web, and it works very well, because if you think about it: a browser opening a web page is just some data coming in (an HTTP GET request), you do something with that data (render a HTML page, fetch something from your database, ...) and you return the result (in this case as an HTTP response). So the flow of a web request, and your controllers in general, becomes very easy to reason about and understand.
Coming back to the BEAM, the Erlang VM was originally written for large scale (as in, country size) telephony systems by Ericsson. The general idea is that everything in the BEAM is a "process", and the BEAM manages processes and their dependencies/relationships for you. So your database connection pool is actually a bunch of BEAM processes. Multi-threading is built-in and doesn't need any setup or configuration. You don't need Redis for caching, you just have a BEAM process that holds some cache in-memory. A websocket connection between a user and your application gets a separate process. Clustering multiple web servers together is built into the BEAM, so you don't need a complex clustering layer.
The nice thing is that Elixir and Phoenix abstract most of this away from you (although it's very easy to work with that lower layer if you want to), but you still get all the benefits of the BEAM.