Basecamp has a really simple pricing for companies. All companies pay the same price, no matter how many users.
It makes all companies equals, none can influence the features/business. If you don't do XYZ we leave with our 5000 users. At Basecamp they are just another client. No pressure.
For simple cases maybe Bridgetownrb which is a static site generator. The twist is that it can have a dynamic part with roda.
For an application I'll use rails with postgresql (reliable and flexible can also store documents).
Redis and sidekiq for background processing.
Turbo, hotwire, stimulus and tailwindcss on the front-end.
Vanilla rails is the best for me. Easier upgrades in the long run.