WCI was the best one imo. At least for Luffy and Nami, that was horrific to watch and back when the BM pirates were a legitimate terrifying force and threat. Luffy almost lost his arms and him and Nami almost burned to death, that really help set the brutal tone for that arc.
I'd say Elbaf is the worst as they're a fucking "Yonko crew" now. It was bad enough how much they were nerfed on Egghead especially a single missile knocked them out of the Sunny and making them so helpless so easily, with a freaking warlord fishman and thus one of the strongest fishmen at least onboard as nakama too.
The Fishman Island one pissed me off a LOT but this one pisses me off more for reasons mentioned already. Oda and his stupid plot induced stupidities and formulas.
If nothing else, whilst it lasts, at least Oda let a female character and an enemy at that shine again and be ultra competent, thankfully. At the expense of the "Yonko level" SHs now too though.
Fun fact, in a filler scene, a kungfu dugong even had haki but half the SHs still don't. Make it make sense.
https://www.reddit.com/r/MemePiece/comments/19d2d9l
The SHs have faced and fought 2 Yonko crews now, CP0 and the GOROSEI, you would think they would all have learned fucking haki by now especially the absolute hell the BM and Beast pirates put them through and and how much Nami, Robin and Usopp got fucked up in Onigashima too for example.
I don't wanna hear any nonsense about "invisible haki" either.