I never early play 3-3 and now we want to try with 2 of my friends. One my friend play dk another playing rdruid. what class should i choose for good results in 3-3?
Most popular is warrior/dk. Other options: survival hunter, combat rogue. If he is unholy, you can try affliction lock or spriest too (but warrior works well with unholy too).
But you can play whatever you'd like--Dk's don't have much CC besides an offensive stun, so you don't really have to worry about DR's. But they are usually used in cleave comps--and they are healer killers.