For versatility and beauty in a single package, I say you can't beat a wrap. It's a bit of an art to learn how to use one, but once you get the hand of it, you can use it for any kid from newborn to 5 years old, and you can carry them on your front, hip, or back, using either one or two shoulders. I'm a big big wrap fan.
My favourite resource for all questions related to babywearing is www.thebabywearer.com, FWIW.
My favourite resource for all questions related to babywearing is www.thebabywearer.com, FWIW.