Breeds that fly well... but even then, based on my backyard predator issues I have lost animals in the past to.I found the Vietnamese jungle fowl I had was the most alert, smart and could fly well bird with a bigger call vocabulary, I miss that hen. But based on her behaviors you will not be catching them once released... she was the flock look out, but not a bird easily wrangled by humans and only hung around because her laying hen flock mates could not fly like her. She liked to roost in a big old Redwood on the top watching the whole area.
She was so different that folks did not even think she was a chicken, most called her a pheasant when they saw her.
Predators are always an issue so even free ranged birds need a secure sleeping spot... things in my suburban area: snakes, hawks, owls, coyotes, foxes, raccoons, skunks, dogs, cats, opossums and once in a while a mountain lion moves into random neighborhoods (about every 5 years in this urban area). So if you are in the country figure same critters plus a few more.
You will need good secure runs for the night and be prepared to hunt a critter every now and then like has been pointed out.
My yard the hens I have are free to run about during the day but at night they go in a totally enclosed mini coop covered run, and it is in solid brick to prevent digging critters from burrowing under, very small wire spacing so bird heads can not be pulled through at night. Nothing sucks more than waking up to beheaded dead birds or coming home from work to a slaughtered flock. I wish I could run hot wire around the coop too... overkill I know for hatchery birds, but hey there my birds, not mister raccoons. There are some new cool products on the market now for free ranging you should check into, like electric mesh fencing...
