I recently caught up to one piece! here's my personal ranking of all the arcs :)

marineford

enies lobby

arabasta

egghead (as of 1086)

levely

skypiea

wano

dressrosa

whole cake island

zou

water 7

arlong park

fish-man island

impel down

post-war

post-enies lobby

amazon lily

punk hazard

sabaody archipelago

whisky peak

long ring long land

return to sabaody

baratie

thriller bark

little garden

loguetown

jaya

reverse mountain

romance dawn

drum island

orange town

syrup village