Well, everyone else has weighed in so I might as well. I just returned from the MOA rally where I tried on a Nolan N90 and it seemed very nice. I also tried on and liked the Scorpion EXO-900. Why am I trying on helmets?
I drank the Kool Aid and bought a Schuberth C3. I'm not impressed. Sure, the build quality is high, but this bit about it being quiet? I find it no less noisy than my Nolan N102 and more noisy than my Scorpion EXO-700.
As others have said, fit is the first priority. The Schuberth fits well, but not as well as my Nolan N102. I've tried a Nolan N103 and the shape is completely different and is impossible for me. My chin rests on the chin bar, which was difficult to close. Anyway, the N90 seemed to fit perfectly. Compared to the Schuberth, the Nolans are much easier to open and close. With gloves on, it's difficult to open the C3 with one had, while stopped at a light, for example. The Nolan's and Scorpions don't have this problem and are super easy to open/close.
Compared to the Schuberth C2 I used to have, the C3 seems to be a big improvement. The opening mechanism is on the front, rather than the side. However, for me, it hasn't been worth the premium it fetches in the market. If it were as quiet as I was told, then I'd like it. But the lack sound proofing (compared the others), the lack of operating ease (compared to the others) and the high price (compared to others) make it a no-go for me.
Again, I'd place the highest emphasis on what fits. But assuming fit is the same, I like the Nolan N90 and Scorpion 900 better for their features. My N102 has been discontinued, but the N90 seems to have improved on anything I would have suggested correcting. Between the N102, C2 and C3 flip ups, I can't tell a difference in the venting. For me, weight hasn't been a big issue, but it seems the C3 is the lightest, followed by the N102 and C2. I think the N90 is about the same as the N102 and the EXO-900 felt heavier. I'm off to look for empirical data now.
good luck, just posting my thoughts. YMMV.