As a matter of taste, I would have to say ShB had the best weapon series because Matsuno was guest writer and they spent a lot of resources on that content. Had that cool Cid's memory Bozja Citadel solo instance, the Varis fight, a few raids and a couple of quite dull field ops instances, but the duels there were an interesting twist. Actually the CEs in those dull zones were very cool too if they popped, like Belias and Shemhazai. Matsuno's Ivalice stuff is some of my favorite stuff in the whole FF series.