It's probably just because he hasn't shown up enough, but I just see no evidence that Sabo would be on even footing. He held his own against Fujitora, he successfully won the Mera Mera, and he wiped the floor with Burgess, but I personally would want to SEE him going all out against someone. He went all out on Burgess, sure, but it wasn't like a chapter long fight.
Basically, I have no idea who wins.