You can see the complete list of
Flutter Favorite packages on pub.dev.

Note:
  Looking to add more functionality to your app?
  The Happy paths project guides you with
  opinionated recommendations for 
  plugins and packages that can take your app
  to the next level.

Metrics

Flutter Favorite packages have passed high quality standards
using the following metrics:

Overall package score

Permissive license,
including (but not limited to)
Apache, Artistic, BSD, CC BY, MIT, MS-PL and W3C

GitHub version tag matches the current version from
pub.dev, so you can see exactly what source is in the package

Feature completeness—and not marked as incomplete
(for example, with labels like “beta” or “under construction”)

Verified publisher

General usability when it comes to the overview,
docs, sample/example code, and API quality