I still say Serena for now hands down, her athleticism is unbelievable plus I have a bias. Her family is from Michigan and moved to Cali, like my family(although I was born in Cali) so Michigan pride haha. My girl is just too much of a beast right now and I am not even that much of a tennis fan but I respect her athleticism. I'm more of a martial arts or football, futbol and basketball guy personally. To each their own though I respect the game of tennis.
Hey I don't blame you for picking her, she is also a great athlete I just have a bias to my girl Serena, Michigan pride Plus I would vote for Serena's as$ as well, the as$ factor. To be fair though Lindsey Vonn is pleasant on the eyes and the best female skiier. I just give the nod to Serena because she has been doing it for a much longer time, so longevity is the difference for me.