Is kaido the best antagonist so far?
Strength and feat wise yes but as character being fleshed out? Nope
What makes this bad is that Oda had 3- 4 years and more than 120 chapters to flesh the main antagonist of longest one piece arc and he still didn't.
If you consider how much FBs Oden, Momo and scabbards got then beast pirates were done dirty.
This literally implies bad writing because oda has his priorities wrong.
Kaido has all the hype around him and Oda neglects fleshing him out for the sake of scabbards and momo which never made sense to me.
Another concern to me is not only flashback is short but it also coming up way too late.
4 pages of flashback for strongest character at the last moments of his defeat
Fans - wahhh this is so good
If kaido flashbacks ends here then oda really messed up kaido.
But this doesn't mean he is the worst antagonist. That's very biased take against him.
We still have caesar and BM who literally spend whole arc screaming Wedding cake