What is the best sign in authentication with google?

Recently im learning about Ionic Google+ Sign in Authenticaion,
but i get a notification that says :
Ionic Auth has been deprecated. As of January 31, 2018, we will no longer provide the Ionic Auth user authentication service.

so, any other alternative for google sign in ?

I think it might just be apart of the new Ionic Services…

You could look at using Firebase to handle this. That is what I use for many of my apps.