To be fair, while i totally disagree with the Sanji vs King parallels because being a flyer and a fire user is complete BS, personality traits typically work for Sanji's matchups.
He tends to fight wacko, essentric personalities who typically are perverts in some way (another reason why it was more obvious he would fight Queen, as was Mr 2 and Absalom). Zoro tends to fight more stoic personalities, who are clearly funny in many ways, but usually are more serious. Pica is 100% serious, it's just his voice that totally ruined that lol.
Zoro also always fights swordsmen, so it's easy to guess who he "may" fight in the future (i.e. maybe Fujitora)