Ruby on Rails has recently started actively marketing itself as the solo developer framework. I've worked with it for a long time now (among a bunch of other languages and frameworks) and I have to say the recent updates to the frontend 'story' are really compelling for a solo dev.

One of the compelling reasons to write JS on the server was to have the same language and ecosystem in the client and server, and things like Turbo for Rails really go a long way towards delivering on that for Ruby (although of course you still need to understand javascript and browsers.)

That said, if you're already familiar with something else, then pick the most mature batteries-included framework in that language. Languages are just a tool for the job, it's incredibly unlikely as a solo dev that you can pick a "wrong" one.