Long ago, we noticed that that Whole Foods chicken was worth the extra $. They are less flabby so there is more nice crispy skin when roasted, and generally tastier. We found similar quality at a small supermarket with an actual butcher.
As an experiment, I bought one at the small supermarket, and a pasture raised chicken at the farmer's market for more than twice as much, and cooked them "beer can chicken," side by side. The pasture raised chicken had almost no flab, and was somewhat more flavorful, but lost the match because it was so dry. Duh. It was frozen, but the supermarket chicken was fresh.
Today we roasted a chicken from the ethnic market where the live chickens are in the back. They are not free range or otherwise fashionable. Just local. Wow. Freshness makes the biggest difference. This was the juiciest yet and very tasty.
I have yet to try pasture raised fresh killed. It will require an appointment out of town at the farm, but according to what I have learned so far, it may be worth it.