Erudite Necros are quite good. Between their innate high INT and having access to some easily attainable items high INT/mana that Iksar Necros can't use (i.e. GEBs, Mantle of Souls, Tome of Miragul) they end up with an enormous mana advantage over Iksars. I made these two Magelos awhile ago to demonstrate this. The gear here is mid-level Kunark era PvP/resist gear, but the mana discrepancy holds until endgame Velious gear. The Erudite Necro has about 500 more mana than the Iksar in comparable gear. That's enormous. This advantage is most expressed in PvP, but the math works out that Erudites are objectively mathematically better than Iksars until regen is able to work for about 15-20 minutes, at which point Iksars pull ahead in efficiency. However, it is doubtful they are ever able to maintain a 20% efficiency advantage when XPing, which makes them level slower despite their regen advantage. It's also worth noting that most 50+ Necro leveling when you're really using charm heavily does not benefit as much from Iksar regen, because you are finishing most kills with a Deflux lifetap anyway, the healing portion of which is simply wasted on an Iksar.
In summary, Erudite Necros are highly underrated. They are not better than Iksars overall, but they are easily a strong second place, and a closer runner up than most people would think.
https://wiki.project1999.com/Magelo_Blue:Iksarmancer
https://wiki.project1999.com/Magelo_Blue:Erudmancer