Duke4Ever19 already said it all very well.
My quick 3 points in favor of Serena are:
1) Court piled up a ton of AO titles against extremely weak fields (and related, before the AO was really considered a 4th major on par with the others)
2) Seles stabbing. Not Graf's fault, but can't ignore it.
3) Longevity - majors spanning 1999 to [at least] 2017!
Regarding #3, I doubt we'll see the likes of this again, as teens just don't win majors anymore. But 30-somethings do. Serena happened to catch (lead?) that transition.
A text without a context is a pretext.