Switched to Elixir/Phoenix a few years ago and have never looked back. Absolutely a 100% improvement on Rails in every way (except the availability of work!)
I revisited rails this past week for the first time in nearly 10 years. So much easier to quickly develop an app on than what I have been doing. I feel done with the whole SPA thing unless there's no other way to build the app.
But now I'm looking at performance, and memory usage, and phoenix looks very appealing from that side.
Now I think I should try pheonix, since both rails and phoenix are new to me, so I can compare.
I don't have a lot of direct experience, but one of the big draws is that by running on top of OTP you get a lot of stuff for free that you'd otherwise need to hit external dependencies for. Caching and background job management that usually see you pull in Redis are the common call-outs.
Also, Phoenix LiveView is absolute voodoo magic the first time you experience it.
But now I'm looking at performance, and memory usage, and phoenix looks very appealing from that side.
Now I think I should try pheonix, since both rails and phoenix are new to me, so I can compare.