I think I should pick mine since I started this thread...
I am seriously drawn towards necromancy, but IRL I would pick arcane magic, because magic is awesome enough without having to risk your life, soul, and sanity for a bit more power. Plus, I'm pretty freaking nice in real life, I feel really bad when I open the food bag in the car and realize I took someone else's order, so I don't think I'd be a very good necromancer.
But seriously, just raising skeletons alone is freaking awesome. Not even zombies, just skeletons, no flesh or traces of humanity about them. The flavor of the dark arts is just scrumptious, which makes me sad at how few times games have TRUE necromancers. I've only played a real necromancer in Diablo 2. Diablo 3 only had the Witch Doctor. World of Warcraft had playable undead but they could only be Warlocks (which, if you know the lore, Undead would be least likely to be). Skyrim did have conjuring, but IMHO, the magic component was just sad in that game. Game designers need to get on this. Just let me raise a skeleton, people!
As for the lightning debate, there were only 8 slots in the poll. Apart from casting lightning, there's not much else in the category of lightning magic, so I don't think it deserves its own slot anyway. Perhaps it fits into arcane.
If magic existed, I'd be the bearded wizard leafing through tomes at the top of his private tower, who, when prompted, gives you amazing advice and words of wisdom.