I have tried a lot of them, and my absolute favorite is the Beco. It works with newborns to children up to 50 lbs - I still use it for my son, who's almost 2. He likes the back carry now (it's like a structured mei tai), which is appropriate for his size.
You should visit www.thebabywearer.com for input about all the different options. I had a Bjorn and a Snugli as hand-me-downs, and I like the Bjorn until it started to pinch into my shoulders. I've also tried the hugabub (different from hugabug!), and that was really nice for the early months, to keep my newborn snug and nestled, but he was a big buy from the start, so it didn't hold up to his weight for long (it's fine - it just didn't feel safe for him anymore).
Becos are expensive, but sturdy, beautiful, and you can do a front, side hip, or back carry - and they can be used to 50 lbs. I have severe back problems, and it's been a lifesaver when my son wants to be carried (and squirm and pull and reach . . . ) because it really distributes his weight well and prevents him from pulling me every which way. He loves it, too - he likes to be snuggled in close and "ride on mommy."