Ranked in these QuestionsQuestion Ranking
Pro Direct downloads on website
The site offers direct downloads on the site itself, though they are a little difficult to find.
Pro Apps not carried on Google Play
This includes mods, module apps, region locked apps, and pre-registered games.
Pro APK downloader app
Using AIO, you can download limited apps and videos .
Pro Safe to download
AIO check every apk file first and compare it's signature to the original one to make sure it hasn't been modified.
Pro Download apks that can't be downloaded from Google Play
Such include the limited apps video downloader and mp3 downloader.
Pro Can provide apk files when the pre-register app came to be released
One of the first of its kind to provide apk files when the pre-register app came to be released. Such include Pokemon Go and Super Mario Run.
Pro Detailed permissions
DownloadAtoZ lists all the permission of the apk file to let you know which permissions on your phone will be used.