I was faced with this decision a month ago and started building my models and views in Rails 7. Late night tinkering with views, then trying out ViewComponent I went 'dude wtf am I doing, these apps are so easy to build in React'... Next.js with Supabase has been a breeze. Setting up db with auth and getting realtime updates and object storage with minimal setup (TS fn calls) was mind-blowing.

Caveats: setting up Supabase auth takes a bit of reading docs, using the js helpers correctly and configuring RLS, but after that it just works.