Well given that most of the mega brewers will not release an ingredients list, we don`t know is it`s cow piss, cat piss, or fish swim bladder, so to be safe I try to stay away.
Besides, living here in NC where there are now so many excellent small breweries, I would be a fool to stick to the mega breweries.
A couple of my favorites are The Duck-Rabbit Craft Brewery and Mother Earth Brewing. Both of these are located <1 hour from my house so I can always be sure it's fresh!