I have never made a build that uses conjuration until now. I made a warrior that uses conjuration to back up. My question is, which side is better the atronachs or the zombie(?) route?

atronachs still the best way....

Both work very well.
Don't use the atronach stone if you plan on summoning your own atronach's,it will absorb half of your summoning spells.
By absorb I mean it will not actually make the summons appear but it will use the required magicka.

Zombies are a lot of fun but there main weakness is that you need to either find or create a dead body in the first place.
To help with this I use a stealth,Illusionist,archery and alchemist character.
There is lots of offense to this character but no defense,it's fun ffor me.

Since you are a warrior,I would go with summoning atronachs.It's easier to do and faster,wich could help the faster paced warrior character.
But as I suggested,just stay away from the atronach standing stone.

Necromancy vs Atromancy(Daedramany)

Necromancy Pro: Less point investment.

Necromnacy Con: You need a dead body to use it.

Atromancy(Daedramancy) Pro: Can use it anytime you want.

Atromancy(Daedramancy) Con: More point investment.

Also summoning is unreliable with spell absorbtion buffs.