Contrary to popular choice, I'd probably change one that wasn't close at all. Something like the RG 2008 final.
Guess with, that kind of ATGs don't grow on trees. You're talking about ATGs level Samprass, Lendl, Djokovic, Federer, Nadal. Even though Big 3 are Gods, they are on level no one will probably achieve anymore.Stan and Murray are inferior specimens who would not win a lot of slams in other eras, these sorta jokers are not ATGs,
Stan is that loser who has been Fedal's pigeon for more than a decade, Murray is another loser who has never beaten peak Fedal in slams
Meddy/Tsitsi/Zverev would never reach the semi finals in other eras too, these are not champions at any level
Actual ATGs below Novak would have made him retire by 2020 and Fedal themselves would be retired by 2018.
Fedal would have stopped winning slams by 2014-2015 and Novak would have by 2018 if real ATGs had arrived in Thiem/Grigor's gen