JC or ENG for blood dk

witch is better
witchs aren't better! they're mean :(
if neither witch ones should i have?
All professions aside from secondary professions are equal in average value besides Jewelcrafting which amounts to a total of +81 primary statistics.
Synapse Springs; 480/6 = 80 ('perpetual' strength)

From a monetary perspective, right now I'd say Blacksmith or JC.
if you can afford to level em go blacksmithing AND jewelcrafting for spiffy gems to put in them extra sockets.

alas, i was stupid and went herbs/inscription, and i shudder at the thought of levelling yet another profession (three 85's, between them max scribe, jc, tailor, chanter, miner, herb)

although i may level an alchemist/blacksmith since my jeweller is maxxed out and i can go farm mats myself with mining/herbs on other toons. got a warrior and a paladin alts, can't decide which to commit to be my 4th 85....
I actually have Tailoring for mine however I only intended to use this for an alt and professions however I have a pally that is a BS and JC so this guy mines. I'm actually going to change to Alchemy since my rogue is an enchanter and herbalist. Truegold is hot on my server esp with the new bs patterns out
Engineering, hands down. The strength on a per second basis is the same (80) but the fact that you can boost it with Pillar is huge.

Also note that if you have haste effect trinkets like Apparatus... you can boost it with that as well so the combination makes it way way better than the rest.
Engineering and JC
You can't use Pillar of Frost as a Blood DK.
Both
If you go engineering, I would suggest not using the damage absorb belt enchant. Unless something changed and I missed it, the backfire is 100% chance to be critically hit, which usually means a tank death. Even if the chance is low, the small absorb isn't worth it to me. The activated armor enchant for gloves is alright, but I don't see a huge benefit from engineering for tanking.