Well, assuming that you are thinking of invading Jonas, I'd go with AV for Ring o'Fire Ritualists, if you aren't intending to construct siege weapons.
Otherwise, OO seems decent too at the moment, your map looks like it does have some decent bit of water on it, and Jonas and the Hippus each has one adjacent coastal city which your cultists could simply singlehandedly take.
Hemah is also on the arcane line at arcane lore which you would be rushing for, for Govannon anyway... so 2 heroes for the price of 1!
Not a huge fan of CoE unfortunately. One advantage of the Amurites is that your priests can learn tier 2 spells once Govannon teaches them the first tier, but unfortunately CoE has no priests.
On that note... another edge of being neutral is that you get access to druids which are instant archmages since they have channelling III.
As for AV and blight.... yes you suffer the same penalties, but u are equipped with the good stuff to deal with it =D
Sac the Weak more or less cancels out the health issues associated with blight, while everyone else suffers.
As for Hyborem.... I usually just wipe him off the map
