Ask HN: Pragmatic choice of server-side web framework

Questions on web frameworks come up often, but I feel mine has slightly more context that I hope others will have more experience in.

I want to build a few SaaS projects on the side to see if they take off.

I want to keep my technology choice pragmatic in order to get something made fast with the desired functionality without creating too many bugs on the way. I'm open to different technology choices (and can pick up any similar backend framework quickly), but there are a couple things that I think are most important:

* Pragmatic: I don't need a SSR PWA SPA with all the newest bells and whistles. I'd ideally like to keep the complexity low. Regular pages with forms and postbacks seem to be the way to go here, with javascript sprinkled in where needed (maybe something like turbolinks if the UX is hindering the product, but I'd like to avoid paying the SPA tax if possible). dotnet core MVC, Rails, and Django seem like the most appropriate options here

* Active: I'd rather not use something abandoned where either bugs in the framework or surrounding libraries will not be fixed.

I don't have a language preference. My framework familiarity in decreasing order is aspnet MVC, Rails, express/sails. Most of these topics say use whatever framework for whichever language/environment you know best, but I could get equally up to snuff in a week or two of evenings with any of these.

I also don't mind using something that is non-traditional if it is the better choice. I've contributed to running Servant, Compojure, React, and Angular projects at various places I've worked.

I'm leaning towards dotnet core MVC or Rails.