It often depends on the make up of your team. Take the following lists into account:
Coverage for Bug + Dark + Poison:
Super Effective: Dark, Ghost, Grass, Psychic
Neutral: Bug, Dragon, Electric, Fighting, Fire, Flying, Ground, Ice, Normal, Poison, Rock, Steel, Water
Coverage for Bug + Dark + Flying:
Super Effective: Bug, Dark, Fighting, Ghost, Grass, Psychic
Neutral: Dragon, Electric, Fire, Flying, Ground, Ice, Normal, Poison, Rock, Steel, Water
As you can see from these lists (thanks to Pokemon Showdown), Aerial Ace hits all of the types Poison Jab hits super effectively and more. So, unless you're playing generation 6 and struggling with fairy types, I'd recommend Aerial Ace. I only say this since you tagged the question with black-white-2 and not something else like xy or oras.
