Ask HN: Best practices for transferring ownership of Google Drive files?

I work for a small company and am curious about best practices for transferring ownership of Google Drive files after an employee leaves. The options I have found are:

1 - Do nothing and don't delete the employee's email address. Only downside to this is continuing to pay for an unused email address.

2 - Change the old employee's sign in name and email address (username) to the new employee's. This should maintain ownership of all of those drive files? Are there any unforeseen issues with this?

3 - Transfer ownership of all the old employee's Google Drive Files & Folders to an employee who isn't leaving. There are lots of horror stories about this-- losing file structure, lost data, etc.

How have other people handled this? What's the best solution and what drawbacks are there?