Is Android 9 a good version?

With the new Android 9 Pie, Google has given its Operating System some really cool and intelligent features that don’t feel like gimmicks and has produced a collection of tools, utilizing machine learning, to promote a healthy lifestyle. Android 9 Pie is a worthy upgrade for any Android device.

Which Android version is obsolete?

Google no longer supports Android 7.0 Nougat. Final version: 7.1. 2; released on April 4, 2017.