I'd start with a .NET 6 MVC application. The default templates will get you started with robust routing and authentication, and you can back it with anything you want for database access. You might find it valuable to start with Entity Framework (EF) - depending on whether or not you want/like to use an ORM. That would provide pretty robust tools for managing database migrations, etc.

It's "boring" but C# is an extremely developer-friendly language these days, and it's hard to beat the availability of documentation, examples, and libraries.

EDIT: and on the front-end, the MVC templates that Microsoft provides start with Bootstrap. I've found Bootstrap and some native Javascript provides more than enough flexibility for quite a while. Bootstrap is great for an MVP, and has a lot of flexibility to make it look good!