It would depend totally on what you plan to use chickens for. If it's one you want to handle on a regular basis, I would advise against dangling by the feet or wings. An old laying hen can be a little delicate. I've seen people pick them up by both wings, too. It works as good as the leg method, but without making them choke or throw up if their crop is full. If you need to grab a bunch of chickens and move them in a hurry, say a limb smashes your henhouse and it's pouring rain, you are not going to kill your chickens by grabbing them and carrying them by the feet. Is it undignified, yes. Does it build a foundation for mutual trust and respect, no. Does it look good in public, no. Is it a good way to transport a bunch of half wild cockerels caught off the roost to the pen to butcher the next morning, well, that is for the chicken's owner to decide.