I would love some more pve elements and random events in the open world to relax to after some good pvp battles.
That said, i feel that diplomacy mechanics are much more important right now (from a pvp perspective). So that gets my vote.
Both choices are needed though, more pve content whether that be missions,events,new kinds of a.i fleets etc is key for the longevity of this game. I say this as mainly a pvp player, when people have nothing to do but sail for hours looking for a fair pvp fight... they get bored/frustrated real quick and we have seen many people leave recently. Give them something to do besides just grinding a.i fleets and we will see many return. As well as giving the rest of us more things to do in-between the pvp action.