All 3 of you have some points. But I agree mostly with
@Zhilady.
Regardless, when talking tennis GOAT (if we HAVE to pick one), objectively there are only 2 candidates currently:
Roger Federer or Esther Vergeer. No other.
GOAT = Roger Federer, (if tennis competition is truly OPEN, regardless of age/gender/physical-condition, and all compete TOGETHER.)
GOAT = Esther Vergeer, (if tennis competitions are separated, and relative-achievement is paramount, kudos
@Zhilady ). She went unbeaten in 470 matches. Yea, THAT good!
To suggest Serena Williams is to try to be PC (and fail) bc in doing so will have completely disparaged Esther Vergeer. ATP tennis is tennis.. WTA tennis is tennis.., but wheelchair tennis is NOT tennis?
tsktsk