Dark vs Cold Damage?

I'm looking for a wand for my Necro and most of the wands are either cold or dark dmg. Which one would be more advantageous? I'm guessing dark because it isn't considered elemental and therefore effective against all targets?

Ignore that comment, Dark Damage is not armor-ignoring.
So I don't think it would be more effective unless you're attacking an enemy with an armor bonus vs. Cold damage.

As a caster you should be casting so the damage type on the wand/staff won't really matter.

It isn't really worth worrying about. Staves and wands do no significant damage, so it's like debating whether you are better off hitting the foes with a feather or a marshmallow. The important thing about spellcasting weapons is the stat enhancements on them.

Dark, holy, and chaos damage types are not "armor ignoring". They are simply damage types that are neither physical nor elemental. Thus, they are unaffected by any armor buffs that are specifically linked to physical or elemental damage. However, the damage is still reduced as usual by the base rating of the armor, by the base rating of any shield equipped, and by any armor buffs that are not linked to a specific damage type.

That said, there is still a slight advantage to dark damage, unless you're using Spinal Shivers, which requires cold damage to trigger it.

actually if u are considering a wand for curses i recomend cold since u can use it to interrupt foes with spinal shivers

Yep I agree would take cold over dark every time, true your not going to be using the wand as a weapon much of the time but the advantages of cold damage interrupts are worth considering.

Also you could convert the damage to any other element which could possibly come in useful at some point.

Over all of those concerns I choose caster weapons for energy and health boosts and for cutting down casting and recharge times of skills.

Caster staffs and wands are spell enhancement items not weapons.

The only situation (of which I know) where staff/wand damage type matters is when you are riding Worms in Nightfall. Equipping a smiting damage weapon does more damage against the awakened. Every other fight you hopefully will not be beating on the monster with your stick so the damage type won't matter.

Weapon-based dark damage is not armor-ignoring. (Skill-based dark damage usually ignores armor.) However, there is nothing in the game that has an armor bonus against it. Cold damage, on the other hand, has a wide number of foes that have either higher or lower than their general armor rating against it.

I'd take a Dark dmg over Cold anytime EXCEPT when I specifically wanted the Cold dmg bonus from Spinal Shivers. You'd be surprised how many foes have bonus armor vs elemental damage or even specifically cold. The majority of them are Ranger profession enemies and their bonus vs elemental damage is HUGE.

Oh, and wanding is very underrated.