If you're brand new to tanking I would recommend warrior. The paladin rotation is very strict and unforgiving, dark gameplay doesn't get good until 72 and requires smart management if resource bars, gunbreaker mitigation is lacking and you need to understand how your 30 second/1 min rotation works to put out quality dmg. Warrior is pretty simple, less buttons, high damage and decent mitigation. You will also start at level 1 allowing you to ease your way into the role. I main DRK but I wouldn't recommend it to new tanks.