Here's my winning trio of baby carriers (and believe me, I've tried MANY!):
1. Moby Wrap - this is my MUST have for a new baby. Perfect for newborns!! Comfy, easy to put on, once you get the hang of it, ready off the shelf, safe for even the tiniest babies, and because you tie it on it will fit anyone large or small with no finicky adjustment needed. When the baby is tiny, no one will even see them - many people thought it was a pregnant belly!! So they don't comment. When people did figure out what was in there, I did get maybe one or two suffocating comments, but I got many many great comments - "so comfy" "how nice for you both" "lucky baby" etc The fabric is stretchy so I don't find it as comfy to wear now that my DD is 23 pounds (she's almost 2 years old!) her weight stretches it out so that I just can't tie it tight enough for it to be comfortable.
2. Hotsling - now that DD is 22 months old, this is the sling I grab as I run out the door. I never got the hang of putting newborns in a sling - I tried several kinds. But once they have the head/neck strength to sit up, the sling is perfect for carrying on the hip.
PROS: I like mine because it is fitted so I don't have to do any adjusting. (And I don't find ring slings as comfortable.) It is small enough to fit in my purse now that I don't have to carry a dipe bag everywhere. It slips on and off quickly and easily. DD is on my hip so that she can look in the same direction I'm looking in (rather than facing me) and I can see her clearly (rather than having her on my back where I wouldn't be able to see her facial expressions.
CONS: Because I use the sling to hip carry, it isn't as comfortable to wear for long periods because my back gets uncomfortable faster than if the weight was distributed evenly. But DD is an active toddler so often she's up and then down and then up and then down running around. This sling is easy to pop her in and out for those times. The other down side is that it is fitted to me, but DH doesn't really do slings at this stage. He baby wore a *little* when the girls were babies, but he's really not into it (!) so I'm the one who uses the sling.
3. Mei tei - I have a baby hawk. This one rocks! I didn't use it for my *very* newborns, but once they were a couple months old I used it daily. This one also ties on so will fit anyone with no adjustments needed. Once you learn how to tie it, it is easy to do. When my girls were little I wore them on front, facing me. With both girls that was my magic trick hold - if we were in public and it was naptime I could strap them in and they would be snuggled up enough to fall asleep, no matter what the noise level. That, in itself, makes this carrier worth every penny!! Once they get older I carry my girls on my back. They LOVE it!! The great thing about this carrier is that it distributes the weight evenly so I can wear it for long, long periods of time without getting uncomfortable. I have even carried my four year year old in it!!!!
I'm not sure I could pick one or even two of these three carriers, I love them all so much. But if I was starting out I'd start with a Moby for the newborn and then see how it goes. All three had a learning curve in terms of getting them on comfortably. But with all three it really only took a couple of tries before I understood how to get it right.