I'm flying on Alitalia to Milan (and onwards) from New York in Business Class. I'd say no to Air France, since they also have a First Class cabin and so your Business Class service might not be as good as it can be.

Delta is likely the best:
AF C-class pitch = 48"
AZ C-class pitch = 55"
DL C-class pitch = 60"

DL also offers codeshare service from ATL to MXP.

Edited to add: I've found no good AZ c-class reviews out there, so I'll review the trip when I get back in March.

[This message has been edited by sowalsky (edited 01-28-2003).]