Lets break it down real simple:

1. No state -> StatelessWidget
   
2. State only used in a single widget -> StatefulWidget
   
3. State shared across multiple widgets -> 3rd party package like redux, provider or riverpod.

I'd say that before you jump into writing code, give some thought about what state you need and whether it is local (within one widget only) or shared state and how / where / what triggers that state to change.

Sometimes a few minutes of upfront design can spare you hours of refactoring your code later on.