This thread has some good points but one thing I'd like to point out is that free range or open range is not "The Best Way to Do It"
It works out for a lot of people. However it is not like you can't have delicious, healthy birds without free ranging them. If I free ranged my birds, they would not taste any better than they do in a tractor that I usually move twice a day and I would have far less of them due to predators.
But tractors aren't trending...free range is