A couple days ago, I put up a thread asking about how many negative levels you can apply in one casting. Some wise soul told me that you can apply as many as 30(!) with an apocalypse oracle casting a critical energy drain, a small negative energy elemental familiar's aura to maximize and a greater rod of empower spell. So that answered that question.
But then my attention turned to the negative energy elemental familiar. It can maximize any negative energy spell within its aura. I immediately thought about how this aura could be further exploited. If a cleric could gain access to it through eldritch heritage (arcane) and improved familiar, he could spontaneously cast inflict spells and harm willy nilly. His channel negative energy ability would also be maximized, making a potent necromancer. He could also gain access to wizard spells through eldritch heritage and gain spells such as wracking ray, which specifically is described as a ray of negative energy.
On the other hand, wizards and sorcerers can access those unique negative energy spells right out of the gate with much less finagling over eldritch heritage. They can also apply metamagic feats much more easily through bloodline mutations, arcane discoveries and arcanist exploits. They can also make use of the improved familiar feat without having to burn two feats to reach it.
So the way I see it right now, going with a divine class can yield more potent results, while an arcane class has access to better resources.
Well, there is always the Void Kineticist and choosing the Negative energy blast. And they get to pick up a familiar with their own wild talents, if they wanted to.