What wand for White?

As the title suggests, what should I be on the look out for "White" wands?

It depends somewhat on your purposes.

Poison Necros should never use White unless they're leveling through the game, at which point +3 to Poison Nova is really all you need. Finding one with +3 Poison Nova +any to Lower Resist can save you skill points early on.

PvE Bone Necromancers will want +3 Bone Spear with some extra cool thing. What exactly that is can vary based on what you find; there's a lot of potential useful stuff. +any to Decrepify or Lower Resist saves you skill points getting to those curses, +summons is nice if you use any tanks, etc.

Summon Necros also don't want White long term, but while leveling it can be nice. In that case, you're most likely looking for a +3 Raise Skeleton and +3 Skeleton Mastery.

I'm not a big pvp person, but I think they want +3 Bone Spirit AND +3 Bone Spear with Decrepify.

Or if hybrid,.+3 Bone Spear or Spirit / +3 Poison Nova / +1 Lower res should be worth a ton too.