I really wish people would stop stereotyping this meat bird.. If they do this, it is your way of raising them that makes them lazy, not the bird themselvesPersonally I don't think breed (excluding cornish cross) has anything to do with tenderness or flavor.
The age of the bird and the activity of the bird is the main factor in tenderness. I've butchered numerous breeds of cockerals. If I butchered them before 14 weeks and kept them confined so they couldn't run all day they were fine cooked using any method. For me much past that age they were too tough unless cooked slowly.
The Cornish cross I've butchered up to 20 weeks still made good fryers. Tenderness IMHO is more a result of the birds activity than age. Why are Cornish so "tender" (personally I find them watery) for so long? Watch them, they do nothing but sit in front of the feeder and eat. They move around very little. Therefore, the result of using their muscles less is a much more "tender" bird.
It's been a few years since I've raised birds a fryers but I do prefer the Freedom Rangers over the Cornish Crosses.

My free range meaties at 6 weeks.
You can see them at 12 weeks here. I haven't uploaded it to youtube, but my birds were anything but lazy. Most delicious chicken I have ever tasted. Very good flavour and the tenderness to die for.