Considering you don't get jumped, "and any good pvper, WILL kill your bot, as much as we like to pretend it's that good, even I.
Blood, hands down, no argument. Less dps substituted for 100% survivability. Can take multiple mobs at once, never need to eat, amazing shields with mastery, you most likely will never see yourself get low, and its SO much fun.
But~ Alas, HB does not, "from what I know of", have any cc's that support blood, which is a serious shame, because it's a solid as hell leveling spec, I guess it's a hint that we should try to learn about the program and not rely on other people to make our dreams come true
But, the next best bet IS Unholy, for HB, "simple dk", is what I use.
Pet takes amazing patrol agro off your back, it has far superior dps, and against caster targets, it can really kick some ass. But once again, it's a glass cannon class, it can take some punishment as long as it has some cd's but it will never save u from 4 mobs grinding at 84 in twighlight highlands
Dk isn't highly supported here, my best advice, is rape AH of the best greens, set er up, and hold onto your balls with plenty of food and expect some often repair bills.
But that's at lvl 84, in twighlight highlands, anywhere else with a much more supported profile will probably give you excellent results
good luck