In current versions of Android, the file system is encrypted from the first boot up. When a factory reset is done, it erases the encryption key. So even if we assume the data we want to recover isn't deleted as part of the reset, it's still in an encrypted state and the key is gone. If, and this is a big IF, there is any recoverable data left, it would need forensics level software to break the encryption. Even that may not be enough.
The default encryption was implemented just for this reason. A test was done on some discarded phones that had been factory reset, and the group found an alarming amount of recoverable data. If the phone was manually encrypted by the user, it wasn't an issue.