I'll be honest, I didn't think he was the best in the world until this season. I knew he was top 3-5 for sure. But the little brainfarts, some bad decision-making made me think he won't go in the Pantheon with Yashin, Banks, Cech, van der Sar or Schmeichel.
But this season...he's so dominant in 1v1 situations. I wouldn't want anyone else between the sticks.
Can you upgrade Alisson? I don't think so.