I prefer the Moby Wrap to the ring slingEspecially when I was a first time mama, I felt really nervous about how secure my baby was in the ring sling. To top it off, both my babies HATED being carried in the cradle position and I never could stabilize their heads when in the upright position of the ring sling. I used the ring sling only for the sitting on the hip position which is useless when baby is a newborn (needs to be close to unsupported sitting to do the hip hold.)
My moby ran me $40. I guess it would be called a stretchy wrap. In fact, it is so simple (a 6 yard length of jersey cotton) I tried to purchase the fabric to make a second one, but could not get the right length and width for a better price.
I like the Moby better than the ring sling because it is softer, more secure, doesn't impede the movement of one arm, and the baby's weight is evenly distributed across the whole back. (I have trouble with the ring sling throwing my back out due to the pressure all on one side--and yes, I spread the fabric out over my whole shoulder and back). Nursing in the Moby is easier than the sling; just wear a shirt that accessible from the top side of the breast (nursing cami's are perfect and s sweater or jacket can be worn over the moby in winter), position baby over nipple and cover the top of breast with the matching bag the moby is packaged in. I did that all summer, at the park, walking through stores, talking to young male check-out clerks (usually the most freaked out about public nursing). Putting the Moby on is daunting at first, but with practice it's pretty quick and easy. Also, since it feels like a shirt you can wear it all day, and slip baby in and out for diaper changes and seated nursing. It even covers your breast well for seated nursing.
The only drawback, if you don't have a distributor or someone in your area to work with you and the baby to practice wearing it, it is really overwhelming to figure it out. In other words, i wouldn't recommend buying it online unless you already know someone who loves it.