Beef feet is the best for me, it does a rich collagen broth, very good to healing and nourishing your skin. I also eat the feet leftover after.
But anything will do, I use all bones from my meat cuts, I do mostly beef and poultry bone broths.
Before starting to cook it, I added 1 or 2 lemons juice to the water and let it sit for 1 hour. Also use the traditional bronua mix of celery, onion and carrot. A little of salt at the beginning and a little of salt and the end. I do slow cooked like french for 12 to 24 hours with low heat. Rich in mineral best supplement for bones health.
Use to cook almost everything, specially soups.
Rephrasing the famous Socrates quote: "All I know is that I know nothing" and about that fact, I am still not so sure.
Greetings! from Jorge from Venezuela.