For starters, I have neither recovery method, but I can give you my interpretation of what Apple says.
Apple does state clearly that its participation in account recovery ceases if you have a recovery key. It does not say anything about a recovery contact. However, I see:
Help a friend or family member as their account recovery contact --> Help a friend or family member as their account recovery contact - Apple Support
" As a recovery contact, you can help a friend or family member regain access to their account if they ever forget their Apple ID password or get locked out. If this happens, they can contact you on the phone or in person with simple instructions for how to generate and share a six-digit recovery code with them. This code, along with other information they verify, can allow them to reset their password and regain access to their account and their data."
This would imply to me that a recovery contact is another way for you to get a verification code and get back into your account which is the primary objective. Your recovery key then becomes moot. If you still have access to your Apple ID and password but have lost your recovery key:
"You can generate a new recovery key from Settings or System Preferences on a trusted device." Refer to the steps in Set up a recovery key for your Apple ID - Apple Support about how to do this on different types of equipment (Apple equipment only).