Google Drive can make your migration from iOS to Android easier
This operation won't exactly run quietly in the background of your iPhone, though. Depending on the amount of data that is being moved, the process could take several hours. During that time, Drive needs to be active and on-screen, so it's best to have your handset connected to a Wi-Fi network and in charging mode.
After the process is complete, all you have to do is to turn FaceTime and iMessage off from your iPhone and sign in to Google from your new device using the account with the backed up data.
source: Android via The Verge