I LOVE a ring sling for a newborn. I much prefer it over a pouch b/c of the adjustability factor. I have a maya wrap ring sling. I like it, but there are others I like better. You can find many other fabric options out there. I have a sling from
www.prettymommaslings.com. It's really wonderful. It's solerveil which is a bit itchy but very very cool. I really have always wanted a zolowear ring sling but my ds is just too big for the investment now!!
Once my ds hit about 5 mos I started using the mei tai. It's an awesome carrier. After they get some weight on them, the 2 shoulder carry becomes super comfy. The mt is awesome b/c you can front carry and back carry. The back carry may sound crazy and hard to do but it really is easy once you get the hang of it. I've been doing it with my ds so long that when I lean forward and throw him up there he just leans into my back until I get situated. It's so comfy to back carry. I do love the front carry best in the mt, though.
At about 10 mos I started using a more structured carrier. I have a patapum and a beco (
www.ecobabies.com). IMO these are not great carriers for tiny babies and while they are good front carriers, I much prefer the mt on the front. What they are the best at is the back carry. At almost 20 mos I carried my ds in my beco around Disney for 5 days. My back never hurt. It is just the most comfy back carrier ever!!!!
So, more info than you wanted, but I think it all depends on the age of your child and what you plan on using it for. If you want something to throw your baby in when you go to the grocery store than a ring sling will take you from the newborn period to toddlerhood. If you want something to take to Disney, I'd go with the ring sling for a newborn, a mei tai for an older infant and a Beco (or patapum or ergo) for an older/heavier baby.
Can't remember if anyone suggested it, but check out
www.thebabywearer.com. Tons and tons of info, reviews, etc on baby carriers.