Login or email

We are preparing a portal for release. Faced the problem of choice: use login or email address for user authorization.
As a result, by brief reasoning, we came to the conclusion that it is better to use an email because:

- email is unique and there will be no case when “such login is already taken”;
- it is more difficult to register a “virtual” (not much more difficult, how much longer);
- it is more convenient for the user - it is not necessary to remember the login under which I registered.

In favor of using the login argument was not found.