It's amazing to see such a mix in reception for the arcs. It just indicates that all of them were riddled with problems and a person's ranking depends on how much they weigh the positive vs negative.
For me it's Dressrosa > WCI > Wano
I tend to weigh the positive aspects as more important, because the better the good parts are, the less I get bothered by the bad. That being said:
- Dressrosa had the best when comparing all 3 in: antagonist, flashback, investment, balance of humour and emotion.
- The 1st part of WCI is not far behind, with probably the best single section (tea party).
- There's little that Wano does better than either of the others...and it's worst is the most unpalatable of the 3. Least interesting antagonists, least emotional investment, worst sidelining of Strawhats, least investment. It's all made worse by the fact that Wano is so unecessarily long on top of everything else. The only thing it may not be the worst in is pacing due to Dressrosa's running around and WCI's wedding cake.
In terms of individual aspects:
- Luffy: WCI > Dressrosa > Wano
- Strawhats' focus: Dressrosa > WCI > Wano
- Antagonist: Dressrosa > WCI > Wano
- Secondary characters: Dressrosa > WCI > Wano
- Tension: WCI > Dressrosa > Wano (based on original reception of course, before everyone seemingly escaped WCI)
- Emotion: Dressrosa > WCI > Wano
- Pacing: WCI >= Wano = Dressrosa
I don't see that changing much at all at this point.