I've already used google, lastpass and microsoft authenticator. Currently, my top choice is Microsoft for 2 reasons:
1) It has a backup option
2) Microsoft is working in a password manager and using Microsoft Authenticator to enable it on mobile devices. I'm not using microsoft password manager yet, but i believe they will improve it in the future. So i keep with microsoft authenticator in case i will use it as my password manager in the future.
This app allows you to backup your 2FA keys to iCloud (AES 256 encrypted). It also allows you to export (backup) your data and store it in your personal cloud. The best feature is that it allows you to store your 2FA keys in folders.
I use to use Authy but something happened with its timing of OTP tokens, so whenever I tried to log into a site where I activated 2FA, the site replied it was invalid. Tech support was useless.
Because of this problem logins become useless, and since I had several with 2FA activated, I became SOL. It took several days, and several emails to site technical support people to reset my 2FA so I could login again, and re-enable the feature.
Since then, I reverted to Microsoft Authenticator for just my Microsoft accounts, and Google Authenticator for everything else. Never looked back.
The moral to all of you who use 2FA is make sure you are using a reliable Authenticator app, and download Recovery Codes as backup. I did not do the latter which made everything worse because I trusted my app never expecting a problem.