F-Droid - F-Droid is an interesting alternative for Android users who want to try something different and not have to use the Goole Play store all the time.
APK Pure - Download apk for Android with APKPure APK downloader. NoAds, Faster apk downloads and apk file update speed. Best of all, it's free
Mobango - Mobango is an alternative Android market.
APKMirror - Android Market and APK Downloads
Blapkmarket - Blapkmarket was one of the largest repositories of the Android apps over the internet that in addition to offering the paid apps of Google Play Store was offering its own developed apps for free as well.
Amazon Appstore - The Amazon Appstore is a place to purchase and download apps for your Android device.