I appreciate you trying, Moxie. I feel bad - you have two really awful Nadal trolls, while we only have one (I'm talking about really bad ones, not just the garden variety fanboyism/girlism
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I'm sticking with my pick of Tsitsipas from the last time this question was asked, despite his recent performance. I think he's got the best combination of mentality, talent, diversity of skills, and experience. Long-term I like FAA, but don't think he'll start winning slams until 2021. But when he puts it together I think he'll dominate the field for a few years.
Zverev has the talent and experience, but his mentality is lacking. Medvedev, Khachanov, and Berretini aren't quite as talent, although have strong mentalities and some experience. But I don't think any of them could beat one of the Big Three in a Slam final, at least not yet. Maybe a worn-down Federer.
I don't think Coric will ever win a Slam - he seems to have a lower peak level than the rest. Same with Edmund, probably Hurkacz. I'm thinking the same of de Minaur, although with a slightly higher level. He might net a Slam if the stars align, but not for a few years.
I still think Shapo puts it all together and wins a few down the line, but he's still pretty erratic.
Not sure about the rest. There's something...soft?...about Fritz. I like Rublev and think he could end up in the Medvedev/Khachanov group, but less consistent. Still not sure what to think about Garin.