- Which faction is stronger? (Necropolis, Tower, or Conflux)

on large maps, Necropolis dominates; I assemble an army of 1.2K or more skeletons, and with proper skill, it's a real headache for the enemy.
Also, could you advise on how to build a Necropolis army – one unit of each type, or two large skeleton units, one Bone Dragon unit, one Vampire unit, and one Ghost unit?