A lot of people have said,
"Wins, because that means you have more experience, and have sparred against everyone."
"Wins, because it's less common to have that many."
I did a separate poll in-game, and counted 32 for wins, and 7 for ratio. I think most of the people that picked ratio, picked it, since it's a lot easier to get 8,000 wins, than 40k+.