winningest
I'm sorry, as a pedant, I have to know how we're defining winningest.
it's ok, i love you just the way you are.
most Grand Slam match wins: 365
most Grand Slam titles, in the open era: 23
These seem very cherry-picked. Wouldn’t like “most wins all time” or “highest match winning percentage” seem like better indicators of who was “winningest,” which seems distinct from who was the best, which your numbers would allude to.
If you just want to talk about who won the most; it’s hard to make a case against Navartalova, especially if you consider doubles tennis is still tennis.