It might give off the impression that baiters or trolls from Zoro's fandom are more toxic- but that's simply because of Zoro has been getting a lot more "gifts" and hype than Sanji ever since, well, a long time now. So these side are the loudest.
For instance, this very minor wing stuff and mistranslated number 2 thing alone led to some Sanji fans insufferably spamming spoilers chat with Sanji > Zoro or them being equals.
And that's just with some mistranslation and symbolic wing statement.
Imagine if Sanji went to the roof.
Imagine if Sanji did what Zoro did to Hakai.
Imagine if Sanji with 30+ broken bones damaged Kaido for life.
You'd see just as much troll flaunting and pretending otherwise is simply lying to yourself.
But, yeah. Toxicity goes both ways. In the end it's better to just ignore it.
I don't think anyone, from either side, has genuine personal hatred towards a fictional character. That'd be pretty sad otherwise.