Don't be like me, choosing to build an entire app on Next.js and hating every moment of it after the honeymoon period ended 2 weeks in. Live and learn.
However, I would strongly disagree with you on the part about it not being suitable for complex applications.
If you feel that way, you can choose to have a decoupled backend (which is what I do with Django) or go all in with full-stack integrations (tRPC in conjunction with edge functions) on top of Next.js.
I have seen great apps built with both of those ideologies.
My Next honeymoon has been going on for a couple years now, and I think it's an AMAZING developer experience compared to anything I've worked with before (Perl/PHP/Laravel/Symfony/Angular/jQuery/React)... it's the framework that made me choose to specialize in frontend because it was so nice. What didn't work for you?
I don't blame you, heh. Every year I feel like the fragmentation is getting worse, not better. It's fun for a while, but makes it really hard to plan for long-term stability and maintainability. It's likely anything I write today will be unusable in 2 years.