Blood dk is generally limited by the monsters running back (evade). If you could find as many mobs as you want, that never ran back blood Dk would be a very clear winner! No competition. But there is no spot where you can pull more than 30-40 mobs (mobs that gives loot), most of the time you only find 20-25 at most, if you search for them. I would probaly use a warlock, if simularly geared just because you have way more dmg output to quickly kill of the limited amount of monsters.