As I see it:
Sabaody part 2 was good, it was especially funny and perfect for a reintroduction arc (short, funny, hype for the future).
Fishman island was meh, one of the worse arcs post times skip (worst after Wano and probably WCI) but still acceptable. Weak intro villain for the post time skip, annoying Jinbe joining / not joining sub plot. Still ok.
Punk hazard was pretty good. Law, Smoker, even Caesar and hus df, the island as a result of the Aokiji vs Akainu fight, dragon df and some hype for Vegapunk.. it could go.
Dressrosa is probably the peak of the post time skip. I didn't especially liked it but hell that G4 moment was good, also Doffy was a great villain (unlike the yonkos later).
Zou was good. Short and good plot/moments. The revelation the minks hided Raizou is one of the best post time skip moments.
WCI was bad, long arc, the Sanji development was done badly (also he gets the raid suit and uses it.. but later destroys it, what?), BM's weeding cake was a nightmare and BM become Big Meme, all the hype and terror she could muster in that shady intro box was reduced to a big walking meme. Also plot power over the roof with half the crew surviving a yonko HQ and beating her YC1 and YC3 plus stealing the road poneglyph...
It was difficult but Wano was even worse. For me this is the arc which killed the manga for good. Now OP is a different manga for me pretty much.
So overall it started good, went down with FI but then the quality improved until Dressrosa and then dived in again until it reached the bottom and started to dig with Wano.