Authy keep the seed so you can recover the 2FA token providing you can still log in to your Authy account.
That's why I use Google Authenticator. I don't want the seed kept (or even known) by a third party. I'll keep my own backup far, far away from any device which also can be used to recover account credentials.
If you use Gemini exchange I believe they only support Authy, at least that's what I had to use. Which is a little annoying having to use both Authy and Google Authenticator depending on which exchange I'm using.
That's why I use Google Authenticator. I don't want the seed kept (or even known) by a third party. I'll keep my own backup far, far away from any device which also can be used to recover account credentials.