Marineford is the best in my eyes. Never have been on such suspense tbh. What are the World Government planning? What is Whitebeard planning? Will Luffy save Ace? The epic amount of high tier people we saw made it awesome as well, we had all 3 Admirals, all the Vice-Admirals, Sengoku, the Shichibukai, Whitebeard, his commanders, and it was just a culmination of epic. It will be awesome animated and some of the fights will hopefully get fleshed out a little bit!
I've only read the 1st and last page but people seem confused on arcs and stuff. So there are 5 Sagas which are made up of a culmination of arcs: East Blue, Baroque Works, Skypeia, CP9 and Whitebeard War. The Saoabady arc is over, it finished before the Amazon Lily arc. East blue is not arc, it's a saga. =p.