Best recovering acc way

[Ahead]

I have to add a "Lost account?" option in my website and after seeing several ways to do it (like with recovery key, with character name, with acc name & email,...) i wonder which of them will work better.

I've heard that recovery key system is the worst as people say it's very "hackeable", ¿what do you think?.

PD: In case you are so fucking kind person, can you advise me about how to add it? (otland guide, etc).

Thank you all .