The boutique chicken you've been buying is largely free range -- which means the chicken has had a chance to exercise. Even large commercial local producers in California like Zacky and Foster Farms allow more room in the cages for their birds than the chickens grown on huge factory-farms in the South for national distribution.
The differences in taste and texture are largely attributable to the chickens' lives. Free range birds are very different from caged birds. Caged birds with big cages are superior to birds who live their lives in small cages.
The feed the birds eat from one farm to another ranch is not all that different. It's grain as far as that goes. Birds who get a lot of yellow corn in their diet tend to show yellow. Agri-business chickens get more hormones so they'll grow faster. Faster growth results in a more tender bird (pound for pound) but less flavor. Because of their conditions agri-business chickens are more susceptible to diseases and receive cocktails of medications to prevent them. There's some question as to whether the use of these hormones and medications are good for humans.
One thing I've seldom seen discussed is the role particular breeds play in terms of taste. Asians can be very picky about what kind of bird they buy for what purpose. Generally, the more boutique the rancher, the more interested they are in choosing breed for flavor characteristics than for cost to slaughter-weight. After space, time is probably the biggest factor. Older birds have more taste.
USDA standards for "fresh" (not frozen) chicken includes holding it at temperatures at which it freezes solid. The USDA says those temperatures are above freezing and therefore the birds CAN"T BE FROZEN. This comes down to "Who are you going to believe, some guy from the board of Sanderson Farms who's a Bush Pioneer or your lying eyes?" At any rate, the non-freezing causes tissue damage at the cellular level which means the birds loose a lot of moisture when they're thawed from their non-frozen state. By the time you get them on your kitchen counter, they're sitting in pools of red tinged water.
The problem is not that the chicken is watery, but the opposite. It's lost water, cooks very dry; and for that reason moves from undercooked (not good with corporate-farm chicken) to overdone very quickly. The best way to deal with this is to brine the meat -- which will make a remarkable difference. A buttermilk bath is not quite as good, but a lot better than nothing. Both of these techniques restore some liquid to the cells and interstitial spaces by the imbalance between the birds' salt and acid levels and those of the marinade.
The hierarchy of not that fresh chickens probably starts with National agri-business, goes to local agri-business, kosher, "organic" (which can mean a lot of things), "free range," and finally "free range - organic."
Freshness makes a big difference in flavor, although most white Americans are too squeamish to want to think about it. The best period for cooking the bird is about 8 to 24 hours after slaughtering. You want just enough time for the rigor to fully dissipate, and otherwise start cooking ASAP.
The best birds in my area are from local Asian/Hispanic slaughterhouses or Asian markets. The customer chooses an appropriate breed and the bird is either slaughtered to order or bought from the case. Birds from the case, it is promised, are better than 24 hours fresh. It is also promised that the birds are more or less local and free range. These jokers wouldn't know "organic" if you hit them with it, but will tell you what you want to hear to make you happy -- if you can get past the language and accent barriers (I'm bilingual in Spanish, which helps a lot). If you want, you can go in the back and choose your own. IMO, it's a good idea for people to accept this level of participation and responsibility once in a while. You may disagree.
The next best source for poultry here are the many Asian supermarkets. (I'm not sure if we even have any specialty poultry or poultry/fish markets in the SGV that aren't fresh slaughter, Asian oriented.) Then, the better Hispanic markets and carnecerias. God knows how the birds are raised, but at least they're fresh.
This is a little different than Berkeley's Gourmet Ghetto, but that's regions for you. You don't realize what a profound effect Alice Waters had on your food choices until you go somewhere else. No, I mean beyond Hayward. Look up, close your eyes, and say, "Thank you, goddess."
At any rate, the price to the consumer for good, fresh chicken is significantly higher than the local chain supermparkets' sale prices -- and one of the three local chians (Albertsons, Vons-Pavillions, Ralphs) is always having a sale -- at least 50% more for carneceria chicken, and 100% for breed-specific Asian chicken. Black chicken is currently running more than $10 a pound at 99 Ranch and $12 from the slaughter guy.