That would be Mana but its a Japanese data center. Neither of the two NA data centers are as active as the Japanese data centers PVP wise (especially Mana) but if you wanna stay in a NA data center you would have no choice but to go to Aether. No one does shatter on Primal, the majority of the PVP populace either not queuing at all or queue only Feast as Feast is still very active on Primal.