I have done my maths comparing Necro Damage with Sorc 2 + WL1 and based in what its yor experience with Sorc 3 I can say Necro do more damage.
The cons of Necro: No mana issues but waste money in Corpses Potions AND dificult to land Flesh Cannon in a pack of mobs without assistance of Linker or Cryo. But Wiz 3 is a must. NO AOE. and Difficult to Solo.
The cons of Sorc 2 + WL is the SP. Similar to the SP usage of Sorcerer 3 but the main problem people dont realize is the CD of Pole of Agony (120 secs) and Dark Theurge seems to hits only 5 times (In the video when a Spirit hits a mob it dissapears). Plus the Pet skill I think will do more dps tan Sorc 3 alone with Moorph. (I assume Sorc2 WL 1 dont morph because is busy casting other spells.) Wiz 3 is a must at last in WL build.
So in clonclusion I think both clases have Cons and Pros, both clases waste a lot of money to fast grind. So if we count how many damage can be done in 2 minutes Necro wins by far, second followed by Sorc 2 WL and finally Sorc3.
The problem of Sorc3 is that dont add much for a new Rank. The damage gain by Int is minimal, and the skills of Sorc3 are useless. Is better option go WL1 and wait what happens in the future with Sorc 3. Because imagine someone goes Sorc 3 thinking when in the future I will be better. But that future change wont give you a free reset skill points.
Personally I dont like the mechanics of Corpse consumption and I dont like the SP drain of Sorc. Plus in my build I dont have Wiz3 so im fuckd off. Even reroll dont seems good because of the mechanics I dislike. The best I can do is follow my original Sorc3 route because im missing Wiz3.