It's so difficult to compare eras but this bint I know who loves tennis reckons that if you could bring a young Borg into the modern era with new training techniques, new sports science, rackets, etc, then he'd be a worthy opponent to the likes of Federer, Djokovic, et al.
Federer probably the best ever but will Djokovic surpass him by the time he's finished? I'd not bet against it. Djokovic to win the final for me although I'm not fussed who wins tbh.
It's same with any sport Mario - how good would Pele, Bobby Charlton, Don Bradman, Jesse Owens etc etc have been in the modern era with better training, diet, tactics, fitness regimes and so on. Interesting question but nigh on impossible to answer.
Impossible to say with complete accuracy however I feel that a supreme talent would flourish regardless. The God given genius is there in all those you mentioned and they would rise to the top in any era.
I have a man crush on Federer such a great player and a true sportsman. Don't think he will win the final but almost certainly the best player of all time.