Honestly, I would prefer artromancy because of the dawnguard and dragonborn summons, that and there is an atronach to go up against everything but, if you would prefer to have two human followers of your choice i would go with necromancy because dead thrall is super fun and you can equip your thralls with any weapon, they get 100 extra health(dark souls perk) and you can raise humanoids up to level 30, level 40 if you are a vampire with necromage.
so whatever floats your boat
Necromancy is probably more problematic, seeing as how you need to have a body present in the first place to even use it. However, in the long run, necromancy is more fun IMO. There's something satisfying about forcing someone who's just tried to kill you to follow you as a thrall.
I love necromancy. The concept is awesome and it can be very useful. I feel like vanilla Skyrim has bland necromancy and that it didn't go in depth but with some mods (since I use PC) it becomes unparalleled. I always have some sort of necromancy on characters too, be it staffs or spells.
As a person who is currently playing as a Bard-ish character, who uses Conjuration. I prefer atromancy. Necromancy, in all views, in game and IRL is WRONG. I find the corpses disturbing and annoying most of all it sounded like they were in agony when they were resurrected. I don't like having someone have their minds twisted just to serve someone. I also felt guilty when I read that Atronachs are actually intelligent. If Tamriel was real, would they hate me for summoning them, or would them like it?
Ask yourself that question and think about it.