google authenticator is the safest. most people who recommend authy are newbs and probably lazy too. coinbase stopped using authy a long time ago and so did i at that time. your phone number can easily be spoofed or hijacked. i admin a really big group and people post that it happened to them all the time. i dont always believe them because there is a ton of bs in those groups, but i am sure some of them are telling the truth.

authy has tried to fix its security issues, but you have to change settings and most people do not do that. even if you do change the settings, i do not believe it is as secure. everyone uses the excuse about losing their phone to justify using authy. that is not a valid argument because all you have to do is back up your restore codes for each site when you set up google 2fa. you should back them up in multiple safe places. i use encrypted folders on flash drives.

you can set up google 2fa on as many phones as you want. you just use the restore code when you set up the other phones.