Really depends on the kind hunt you are doing.
I talked to one of our local places just the other day while putting a hunt together for some friends. This is at a set n' get club, not wild drive. For the set n' get, he said 2 3/4 low brass in anything from 6 to 7 1/2 work. I picked up some 1 1/8 #6 lead today at my local shop, only because they didn't have any 1 1/4. Running a modified choke it patterned pretty good at 40 yards. I'll bring some 7's just in case we decide to do some smaller birds also.
If I was going to do a wild drive, I'd go with any of the other recommendations heavier and more powerful shot where the birds will be more energetic.
