Aegis works the best for me, it is specifically for power users because it allows sharing of the seed phrase quite easily. So may not be for users who don't understand that part. But for me has been a godsend. I am trying to get my parents on a better 2fa standards. And it works because I scan and setup 2fa first on aegis and then share it to their authy. They find authy useful and I'm not worried about them accidently sharing seed phrase.

For backups, aegis does automatic backups to local storage and next cloud syncs it to my cloud. It is encrypted so you can use something like foldersync to sync it your gdrive or mega or something like that.

Aegis is not multi platform, but I honestly don't care, in my opinion it's better to have aegis on my phone and when I need to login from a desktop, looking up the code in phone is a separate device factor which adds on to the security. Meaning if somebody knew my passwords and stole my laptop, they'll still have to steal my phone to access 2fa. Different story if they steal my phone though.