Oh sorry, for some reason I missed the "ever" part.
Yes Alisson is among the best keepers ever.
A lot has changed in 40 years, though. Keepers today are a lot fitter and need to use their feet more. In some teams they almost act like the deepest playmaker on the pitch.
30 years ago Neville Southall stood in goal and looked like this:
So yeah, for me it's a keeper who played between 1998 and now.
Unfortunately, he played for Man U.
Van der Saar