like the necromancy wizard is obiously the archetypical necromancer, but the divine soul sorcerer has some unique tricks that give it certain advantages over the more traditional choices, as shown below:

Necro Wizard:

• the wizard has a bunch of unique thematic spells for necromancy that only wizards get, stuff like clone, soul cage, and a few non necromancy spells also exclusive to wizards that have to do with souls like similacrum and create homunculus
• necro wizards will generally have stronger minions that deal more damage and have more health due to that one class feature
• the abillity to regain hit points from necromancy spells fits nicely with hit point manipulation spells like eneveration, vampiric touch, life transference etc
• wizards can also cast summon greater demon, giving them acess to two demons in particular from morekinens tombe of foes, the dybuuk that can posess corpses and a demon that can ressurect fallen ghouls and ghasts that you have animated, as long as you use planar binding, magic circle and maybe possibly if nessesary an hallow spell from an bribed fiend warlock or death cleric (or by using wish to replicate the spell) to prevent an dybuuk from at will teleporting out while you are still trying to bind it
• xanatar's guide to everything grants several mid combat necromancy spells useful for an necromancer in great peril, like eneveration for extra health, danse macabre for fast animation, negative energy flood ether to create an temporary little minion or to buff one of your undead minions
• 18th level capstone lets you equip your entrie army with non concentration 1st and second level spells like longstrider, mage armor, darkvision, nystuul's magic aura etc to give you that extra boost
• injured to undeath seems to be a mere defensive tool, but it can be helpful with create homunculus and to create an more controlled enviorment for life transference
• command undead lets you premanently steal an mummy lord if they fail their save, giving you an permanent spellcasting slave

Divine soul Sorcerer:

• due to having all cleric spells and all sorcerer spells, an divine soul sorcerer can have both animate dead and finger of death in their arsenal like a wizard. By using twinned spell metamagic on finger of death you can create twice as many permanent zombie minions per day as a necromancy wizard can with the same spell, and by using your sorcery points you can create more spell slots and thus reassert control over far more undead minions than what the wizard will ever be capable of in a single day, your minions are not strong but they are many
• divine soul sorcerers can also resurrect people, raising them form the dead. This is the entire point of necromancy and something the necro is incapable of
• while their features are not as thematic as necro, your higher level ones do let you go arround with cool bony skeleton / bat wings and cheat death in the highest manner
• your combo of cleric and sorcerer spells also give you some neat buffs like aid that you can utilize to make up for the lacking defensive capabillities of your minions
• wish can be used to replicate any wizard spell you lack and make up for your limited spells 
• while the 20th level capstone is generallty bad, it does let you sit in a library forever, taking many many short rests and turning all sorcery points into spell slots, once you come out of your cave after a week you will have like ten or maybe even twenty 5th level spell slots for your to use in world conquest, so not entirely useless

i will leave any assessment of their capabilities up to you, but i will say that i think divine soul makes an pretty rad option for an necromancer who wants to support their team. It would be neat to have an party consisting of one of each and then an oathbreaker paladin for their buffs as well, the divine soul supplies the numbers, the wizard supplies the elite fiendish and undead troops and the oathbreaker buffs those elite troops to greater heights than before with aid, crusader's mantle and some aura spells

I'm personally taking divine soul, as I tend to view necromancy a life-magic and heals dovetail perfectly with this idea.