Only a few people had won multiple Slam over the age of 30. And it’s all are the candidate of the Greatest Player of All Times also: Federer, Nadal, Djokovic, Laver, and other players I forgot. I’m pretty sure Wawrinka won 2 Slam when he’s over 30. But he out of contest for the greatest player. So it’s really between those 4 Great.
I pick Federer right now, simply because he won more slams when he’s over 30. But of course Nadal and Djokovic can pass him someday, maybe… But right now, it’s Federer.
In the women’s side, it’s really no contest: Serena Williams. Even after she gave birth, she still have multiple Slam finals. Not as great as Clijsters when it’s about mom’s greatest player… But to do that in 37 years old! Serena still have what it takes. It seems that her loss at US and Australian Open only makes her angry and hungry. You see what she capable of when she’s in that situation… some crazy stats which included dominating tennis on the court and collect multiple slams. And I knew she’ll do it again this time…