OK, Medvedev. I don't feel like I've watched him enough to really assess his game -- although will say that he seems to have more of a complete game than it at first glance, even from earlier this year. He's forever linked with Khachanov in my mind, as they are very close in age, tall Russians, and came up at the same time - even leapfrogging each other for awhile. From the get-go I preferred Medvedev, even had a hunch he'd be good (although not this good), but then Khachanov had his run last year, won Paris, and seemed like he would be the better player. But Daniil has exceeded all expectations this year.
That said, I'm not quite ready to crown him the next great player, or even next #1. I do think he will win Slams, be a regular in the top 5, and maybe even reach #1, but I still think Tsitsipas and FAA have more potential.
That said, the AO should be interesting. I'm hoping we see a new (Next Gen) Slam champion, and Daniil seems the top contender.