For me it's
WCI > Zou > Punk Hazard = Dressrosa > Fishman Island
Still waiting for Wano to finish up before I rank it cause an ending can drastically change my opinion on something, but rn I'd put it between Zou and PH/Dressrosa
Some explanations for my rankings:
WCI: This is tied with Water 7/Enies Lobby as the best One Piece arc imo. It had a great storyline, an interesting setting, emotional moments, great antagonists, meaningful character growth, and the single best 1v1 in the entire series so far. I really loved Sanji's storyline, I loved getting to see Brook and Nami do cool shit, I thought Big Mom and Katakuri were fantastic antagonists, I thought Pudding was great, and I loved getting to see an actual naval battle (which we don't see nearly enough of since this is supposed to be a manga about pirates). Though I guess if there's one thing about it that I didn't like, it's that it takes a while to really get going.
Zou: Really great arc. Zunesha was a cool setting and I liked how the arc was kind of a mystery where they needed to piece together what happened beforehand
Dressrosa: Overall I liked this arc, but it did drag on longer than it needed to imo. Really liked Law's role in this arc and Doffy as a villain. Liked the God Usopp thing a lot but wasn't a big fan of Usopp needing to repeat his character arc from earlier in the series. Really liked Franky's role and imo Franky vs Senor Pink was one of the better fights so far. Kinda wish Robin got a bit more spotlight, but I guess her role this arc wasn't too bad. Also it had Bartolomeo and Cavendish, which is obviously a big plus. Don't have any major complaints with the arc other than the fact that I thought the setting was pretty boring. It's kinda hard to make fighting in a city for 50 chapters visually interesting.
Punk Hazard: I think this arc went on longer than it needed to, but overall I thought it was solid. Really liked Punk Hazard as a setting. Liked getting to see Smoker and Tashigi again. Law cutting Vergo was, of course, great. My favorite thing this arc though was some of the Strawhat interactions with their bodies getting swapped.
Fishman Island: I loved Jimbei's flashback, but other than that this arc was just kinda okay for me. 5 or 6 out of ten