I'd go to A Voce. It is wonderful and the food is fantastic, atmosphere is good. Get the duck meatballs (I think that is what I had that was so amazing). I didn't think it was noisy at all. I went on a date there and it was perfect.
L'Impero is also a great choice. You really can't go wrong either way.
We've not been to Babbo, so I can't make any comparisons.
We've been to A Voce just once not long after it opened last year and, though we thought the food was excellent, we have not returned for one reason: the hideously high noise level. I do not find being assaulted in that way, to say nothing of having to shout in order to carry on a conversation, a comfortable way to dine.
As for L'Impero, I love it! As I've mentioned on several other threads, we just had dinner there, the second time since Michael White took over the kitchen, and I think his contemporary Italian cuisine is superb! The menu is more hearty now than it was in August, as it should be. Also, in August, my sole qibble was with dessert, which I found disappointing. However, there has been a pastry chef change, and desserts have improved immeasurably. There's an excellent wine list, service is friendly and capable, and the surroundings have an understated elegance, yet there is not a hint of stuffiness. The noise level can be on the high side when the restaurant is full but, happily, it never gets to the point of being uncomfortable. In my view, Bruni's demoting L'Impero to two stars was off-base. I think White's cuisine is at least as fine as Scott Conant's, if not better, so L'Impero remains, for me, a three-star restaurant.
The food at A Voce is fabulous - as good as it gets here in NYC - and certainly on par w/Babbo, etc. BUT - it is a hard reservation to get AND it is LOUD - all hard edges - it'll be tough to get a good table in the front, you may consigned to the rear, nearer the johns. But, the food IS fabulous!
Bruni/NYT just reviewed Alto and L'Impero - 3 stars to Alto, 2 to L'Impero
I think so. Atmosphere, however, will be an important factor here though. A Voce is more modern and interesting...L'Impero is a bit stuffier. Both serve excellent food. I've been to L'impero two or three times (I honestly can't recall, I think three) and A Voce once. Prior to the changes in chefs at L'Impero, I'd go back to A Voce before I went back to L'Impero...but because of the chef change...its really a draw. And thus, I'd have to base it on atmosphere and convenience...so I'd probably choose A Voce.