Google Play store versus Amazon app store

If you are targeting Kindle Fire tablets and the Kindle phones, you should release your app through Amazon app store because it is the default app store on those devices and will give you exposure when users search apps. If you are only targeting Android devices, Amazon app store is not a must-do. It is just another distribution channel. It has some promotional features that you may want to take advantage of such as the Free app of the day/week etc. Some white label Android tablets also uses Amazon app store as their default app store.