I don't think I'd use my ring sling for a newborn, though it's all I've used since DD2 turned about 4 months. She's not keen on the mei tai at all as she prefers the hip carry. Before the ring sling we used stretchies.
DD1 however, hated the ring sling until she was about a year and a half old. She absolutely loved the mei tai and was in one from roughly 4 months until she went in the ring sling.
It really will depend on the baby, and on what you're more comfortable with. Do you have a sling library near you that you could perhaps go to?