I love, love, love the Beco Baby Carrier! I have a 4th Generation which requires an infant insert (like the Ergo does) for newborns but can be used without one between 3-4 months. The new Beco Butterfly has a built-in panel for newborns. Besides being great for your back, easy to adjust and figure out, and very secure for the baby, they come in gorgeous patterns. The Beco is a lighter and thinner than the Ergo. See my review here. I like them both.
I bought my 4th Generation from SoBeBabies. They have excellent customer service and right now they are having a great sale on the Beco Butterfly. They are an authorized retailer and this is the first authorized sale.
This carrier is pricey, but it is worth every penny. I used mine all the time (instead of a stroller) until my son was 16 months old. I still use it with him, but not as much because he is older and wilder (almost 23 months). Still, it can support his weight. It is so much easier to put a baby in a carrier like this and do laundry or shop then get out the stroller or lug the infant carseat. This is one item worth investing in.
I bough the Baby Bjorn first and that carrier is much more difficult to use and hurts my back and shoulders when Ian was about 10 lbs. I tried a ring sling and a pouch, but I couldn't get him positioned correctly. Some people swear by them, but I like two-shouldered carriers better. Some people love mei tais, which these carriers are inspired by, but you need to tie and untie mei tais. With the Beco and Ergo, you just click the buckles and pull the straps to adjust. Fast and easy to get the baby in and out.
There are lots of other carriers out there now (an explosion has occurred in the last few years), but I have throughly tested both of these. I've breastfed in them while climbing a mountain in the desert in Egypt, used them through international airport security lines and dodging traffic in Egypt. They rock. You need them.