If i were to make a DK

if i were to make a dk what spec should i choose
I'd go Blood for leveling. Decent self heals so you can keep a good flow going with little to no downtime. Plus it's the tank spec so if you are in to that sort of thing, you can tank dungeons with insta-queue's. If not, dual spec and grab unholy to DPS them.
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I have a blood/unholy dual spec for levelling.....Blood is excellent for survivability and Unholy has good utility even at initial levels. I found frost too bursty at lower levels but haven't tried it since 4.1 buffs and with dark succour. Also with frost you dont get your main strike till around lvl69 (HB- the 31st talent point).
I personally leveled as blood/unholy. Just now am i discovering the wonders of frost.

Blood has the best survivability and the insta tank ques. Did group quests and such with it. I also used blood, when i first hit 80 and went to cata areas. Those starting mobs do hit hard with the initial gear you go into cata areas so blood shines there.