I've noticed that deadlifts are one the "big 3" necessary workouts. Does this include any type of deadlift?

Right now I do the type where your legs are spread out and you bend at the knees. However, I'm willing to add/switch to the stiff legged deadlifts if I hear that they are more popular.

I have to admit that out of any exercise, I am seeing the most results with deadlifts (I'm only 5'5", 140lbs, and I can deadlift 320 so far).