What's quietest for someone else may not be quietest for you. There are lots of variables, and one of the biggest is how the helmet fits your head. So what's quiet on someone with a round head may not be for someone with a more oval head. Someone with a squat head may have a totally different reaction to a helmet than someone with a taller head. A lot of helmet noise comes from air that gets up underneath the helmet, so one that fits you tightly there will probably be better than one that's looser: again, that depends on the shape of your head.
Many people buy helmets based solely on price and style. That means that if it doesn't fit their head shape properly, they buy the next larger size. A helmet that's too large is going to be noisier, because the loose fit will let more air up inside it.
Reacting to FirstPeak, what's most comfortable for someone else might be terrible for you, again because of head shape. If he's got a rounded head, and you've got an oval head, it's unlikely the same helmet will fit you both well.
Check out the helmet review on webbikeworld.com. You'll find a lot of good info on noise, and helmet shape, there.
To answer the original question, probably the 3/4 helmet branded as a Yamaha that I had back in the mid 70s. The quietest full face was probably my original Bell Star. No vents, the shield snapped down with a tight seal, and a smooth egg shape, with no protuberences, wings, slots, or other noise making items.